To investigate the expression of Fas, FasL mRNA and proteins on keratinocytes and fibroblasts, and the influence by retinoid acid (RA) and dexamethasone (Dex) Methods RNase protection assay and flow cytometry were used Results Fas mRNA was expressed on neonatal murine keratinocytes and was up-regulated by all-trans retinoid acid and down-regulated by Dex RA and Dex also increased the Fas protein expression on keratinocytes Newborn murine keratinocytes express FasL mRNA, which was up-regulated by RA and Dex, while its protein expression was moderately induced by RA Newborn murine fibroblasts also expressed Fas and FasL mRNA, which were up-regulated by the RA and Dex Conclusions The results indicated that RA and Dex might regulate apoptosis of keratinocytes and fibroblasts via the Fas-FasL system To investigate the expression of Fas, FasL mRNA and proteins on keratinocytes and fibroblasts, and the influence by retinoid acid (RA) and dexamethasone (Dex) Methods RNase protection assay and flow cytometry were used Results Fas mRNA was expressed on neonatal murine keratinocytes and was up-regulated by all-trans retinoid acid and down-regulated by Dex RA and Dex also increased the Fas protein expression on keratinocytes Newborn murine keratinocytes express FasL mRNA, which was up-regulated by RA and Dex, while its protein expression was moderately induced by RA Newborn murine fibroblasts also expressed Fas and FasL mRNA, which were up-regulated by the RA and Dex Conclusions The results indicated that RA and Dex might regulate apoptosis of keratinocytes and fibroblasts via the Fas-FasL system