The effect of male and female sex steroid hormones on the proliferation of both male and female epidermal keratinocytes was investigated in cells cultured in a completely defined serum-free medium. Growth was assessed by clonal growth assays. The clonal growth of male foreskin-derived keratinocytes was strongly inhibited at micromolar concentrations by both 17-β-estradiol and progesterone, and had only a moderate inhibitory effect on the clonal growth of female adult skin-derived keratinocytes.

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... By contrast, clonal growth of either male or female keratinocytes was unaffected by micromolar concentrations of testosterone. Morphological studies provided additional support for the effect of female sex steroid hormones, showing drastic decrease in cell number, abnormal cell morphology and altered colony and cell arrangements. Evidence is provided for a specific and saturable 17-β-estradiol receptor present of the surface of male-derived suprabasal keratinocytes challenged by unlabelled competitor male and female sex steroid hormones: estradiol, estriol, norethistrerone, levonorgesterol and testosterone in a radio-labelled 17-β-estradiol binding assay.