Fig. 4. Decreased cytokine receptor and TGF- expression in HaCaT cells. (A) Expression of KGF and GM-CSF receptors as well as of TGF- were determined in organotypic fibroblastco-cultures of keratinocytes (NEK) and HaCaT cells by semiquantitative RT PCR using GAPDH expression as internal standard. The RNA expression profile is representative of duplicate determinations of three independent experiments. (B) TGF- concentrations in culture supernatants of 3-7-day-old co-cultures of NEK and HaCaT cells with postmitotic fibroblasts were determined in aliquots of 2-day-conditioned media by ELISA and calculated as pg/10⁵cells. Bars represent means ± s.d. of duplicate measurements performed in three independent experiments.