Figure 11. The effect of 7DHP, pregnacholecalciferol (pD3) and pregnenolone on normal immortalized epidermal HaCaT keratinocytes and PIG1 melanocytes.

A and B. Inhibition of HaCaT cell proliferation as measured by [³H]-thymidine incorporation (A) and MTT (B) assays after 48 h and 72 h of treatment, respectively. C. Inhibition of NFκB activity in HaCaT keratinocytes 24 h after transfection with luciferase construct NFκB-Luc. The cells were treated for 24 h with 100 nM vitamin D3 (vD3), 1,25(OH)₂D3, 7DHP, pD3, pregnenolone or ethanol vehicle (control) and luciferase activity was measured in cell extracts. D and E. Inhibition of cell growth as measured by sulforhodamine b assay (protein content) after 72 h of treatment of non-pigmented (D) and pigmented (E) PIG1 human melanocytes. Inserts show the color of representative cell pellets. Significant differences versus ethanol-treated control cells were defined as *p<0.05, **p<0.01, ***p<0.001.