Fig. 1: Tpl2 ^−/− keratinocytes have an increased cell cycle, propensity for malignant conversion, and HGF and MET expression compared to Tpl2^+/+ (WT) cells.

a WST-1 viability assay for v-ras^Ha-transduced Tpl2^−/− and WT keratinocytes (RAS) grown in conditioned media from Tpl2^−/− or WT fibroblasts. Results normalized to the v-ras^Ha-transduced Tpl2^+/+ (WT) keratinocyte control. *p < 0.05, **p < 0.01. b v-ras^Ha-transduced WT and Tpl2^−/− keratinocyte malignant conversion in response to fibroblast signaling. v-ras^Ha-transduced WT (“i”) or Tpl2^−/− (“ii”) keratinocytes cultured in high calcium media develop no foci and remain quiescent in a dispersed monolayer which can be seen at 4X (“iii”) and 40X (“iv”) magnification using rhodamine staining. WT (“v”) and Tpl2^−/− (“vi”) keratinocytes cultured in high calcium fibroblast conditioned media form proliferative foci. Foci from rhodamine-stained cultures stain brightly (“vi”, 4X magnification; “vii”, 40× magnification) under fluorescence microscopy. Real-time PCR quantification of HGF in keratinocytes (c) and immunoblotting (d) of HGF in untreated and v-ras^Ha-transduced Tpl2^−/− and WT keratinocytes. Immunoblotting of HGF in fibroblasts (e) and immunostaining of HGF in skin (f). Real-time PCR quantification (g) and immunoblotting (h) of p-MET. *p < 0.05