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29 Oct 2026

A431 cells

Published: 17 October 2023  |  Last reviewed: May 2026

A431 is a human epidermoid carcinoma cell line derived from the skin of an 85-year-old female patient. It is one of the most widely used cell lines in biomedical research, particularly in cancer biology, immuno-oncology, dermatology, and drug discovery. A431 cells massively overexpress the epidermal growth factor receptor (EGFR) — carrying approximately 2–3 million receptors per cell, roughly 20–50 times more than normal epithelial cells — making them the gold-standard in vitro model for EGFR signalling studies and the testing of EGFR-targeted therapies such as cetuximab and erlotinib. A431 cells are available exclusively from Cytion, your independent European cell bank.

📋 A431 Cell Line — Quick Facts
📋 Contents
  1. A431 cells: General characteristics and origin
  2. A431 cell line: Culturing information
  3. Advantages & disadvantages of A431 cell line
  4. Research applications of A431 cells
  5. A431 vs. other skin cancer cell lines
  6. Research publications featuring A431 cells
  7. Resources, protocols, and videos
  8. Frequently asked questions

A431 cells: General characteristics and origin

This section covers the key biological properties of the A431 cell line that you need to know before working with it — including its origin, morphology, karyotype, and the EGFR overexpression that makes it uniquely valuable for research.

A431 Cell Line Origin and History

  • A431, a human skin cancer cell line, was obtained from the epidermis of an 85-year-old female epidermoid carcinoma patient [1]. It was established by D.J. Giard et al., who developed several other cell lines from solid tumours.
  • The cell line has been widely distributed and validated by independent cell banks worldwide, including Cytion, as a reliable and reproducible research model.

A431 Morphology and Karyotype

  • A-431 cells possess epithelial morphology. They aggregate and form cell clusters under standard culture conditions.
  • The A431 skin cancer cell line is hypertriploid. The modal chromosome number is 74, occurring in approximately 36% of cells. Higher ploidies are also present in around 1% of the cell population.

EGFR Expression in A431 Cells

EGFR overexpression is the defining characteristic of A431 cells and the primary reason for their widespread use. A431 cells carry a genomic amplification of the EGFR gene locus, resulting in approximately 2–3 million EGFR receptors per cell — 20 to 50 times higher than normal epithelial cells. This makes A431 the gold-standard positive control for:

  • EGFR antibody validation by Western blot, flow cytometry, and immunofluorescence
  • Testing EGFR-targeted monoclonal antibodies such as cetuximab and panitumumab
  • Evaluating EGFR tyrosine kinase inhibitors (TKIs) such as erlotinib, gefitinib, and afatinib
  • Studying downstream signalling pathways including PI3K/AKT/mTOR and RAS/MAPK/ERK

Tumour growing under the skin and infiltrating the underlying tissues — A431 xenograft model illustration.

A431 cell line: Culturing information

Knowing a cell line's culture requirements makes handling trouble-free. This section covers the doubling time, growth medium, passaging, cryopreservation, and biosafety requirements for the A431 cell line.

Key Points for Culturing A431 Cells

A431 epidermoid carcinoma cells forming spheroids at different densities

A431 epidermoid carcinoma cells forming spheroids at different cell densities.

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Advantages & disadvantages of A431 cell line

The A431 cell line possesses distinguishable characteristics that make it both highly useful and contextually limited. Here is a balanced summary.

Advantages

The main advantages of the A431 cancer cell line are:

Disadvantages

The disadvantages of A431 cells are:

Research applications of A431 cells

The A431 cell line is extensively used across multiple research disciplines. Its unique EGFR biology, tumorigenicity, and well-characterised genome make it one of the most versatile human cancer cell lines available.

  • Cancer biology: A431 is a powerful tool for investigating cellular and molecular mechanisms driving cancer growth, metastasis, and invasion. Studies have extensively mapped the PI3K/AKT/mTOR and RAS/MAPK/ERK signalling pathways in this cell line, with inhibition of these pathways shown to induce apoptosis in A431 skin tumour cells [2, 3].

  • EGFR-targeted therapy testing: A431 cells are the reference standard for evaluating anti-EGFR therapeutics. Researchers use them to assess the efficacy of monoclonal antibodies (cetuximab, panitumumab) and small-molecule TKIs (erlotinib, gefitinib, afatinib, osimertinib) in blocking EGFR-driven proliferation and downstream signalling.

  • Drug testing and evaluation: A431 cells are used to evaluate the antiproliferative efficacy of novel drug candidates — including nanoparticle formulations, plant-derived compounds, and biologics. A 2022 study by Rahim et al. demonstrated that biogenically synthesised silver nanoparticles from Alstonia angustiloba exerted potent antiproliferative effects on A431 cells [4].

  • Tumour xenograft models: A431 cells are tumorigenic in immunodeficient mice, enabling the development of subcutaneous and orthotopic xenograft models for in vivo efficacy studies. Lim et al. used A431-derived xenografts to evaluate the radiosensitising effects of exogenous EGF in vivo [5].

  • Skin toxicity and dermatology research: A431 cells are widely used by pharmaceutical and cosmetic companies to assess dermal toxicity, skin penetration, and the safety profile of topically applied compounds, including sunscreens, retinoids, and novel actives.

  • 3D spheroid and organoid models: A431 cells readily form compact 3D spheroids under ultra-low attachment or hanging-drop conditions. These spheroid models better mimic in vivo tumour architecture — including hypoxic cores and diffusion barriers — making them ideal for evaluating drug penetration and resistance in a more physiologically relevant system.

  • EGFR antibody validation: Due to their extreme EGFR density, A431 cells are the standard positive control for validating anti-EGFR antibodies in Western blot, immunofluorescence, immunohistochemistry, and flow cytometry applications.

A431 vs. other skin cancer cell lines

Choosing the right cell line is critical for experimental validity. Here is how A431 compares to other commonly used skin and squamous cancer cell lines:

📋 A431 cells — Quick Facts

Research Publications Featuring A431 Cells

Here are some significant peer-reviewed publications featuring the A431 skin carcinoma cell line.

Efficacy of biopolymeric PVA-AuNPs and PCL-Curcumin loaded electrospun nanofibers and their anticancer activity against A431 skin cancer cell line

Published in Materials Today Communications (2020). Evaluated the anticancer potential of poly-ε-caprolactone curcumin-loaded nanofibers and polyvinyl alcohol-AuNPs against A431 cancer cells.

miRNA-221 promotes cutaneous squamous cell carcinoma progression by targeting PTEN

Published in Cellular & Molecular Biology Letters (2019). Proposed that microRNA-221 plays an oncogenic role in cutaneous squamous cell carcinoma by targeting the PTEN tumour suppressor gene.

Fungal vincristine from Eutypella spp-CrP14 isolated from Catharanthus roseus induces apoptosis in human squamous carcinoma cell line A431

Published in BMC Complementary Medicine and Therapies (2016). Showed that vincristine from the fungus Eutypella spp–CrP14 induces apoptosis in A431 cells.

Overexpression of CDC42SE1 in A431 cells reduced cell proliferation by inhibiting the Akt pathway

Published in Cells (2019). Identified CDC42SE1 as a potential biomarker of skin cancer progression, with its downregulation facilitating tumorigenesis in A431 cells.

Metformin inhibits the proliferation of A431 cells by modulating the PI3K/Akt signaling pathway

Published in Experimental and Therapeutic Medicine (2015). Demonstrated that metformin suppresses A431 proliferation by regulating the PI3K/Akt signalling pathway.

Resources for A431 Cell line: Protocols, Videos, and More

The following resources provide practical guidance for working with A431 cells in the laboratory.