CPT inhibits COL1A2/CAT promoter activity. Human dermal fibroblasts were transiently transfected with 20 μg of COL1A2/CAT promoter construct and treated with CPT (at 10-12 to 10-6 mol/l) for 24 h. Samples of cell extracts were normalized for protein concentration. Comparisons of the promoter transcription activity after CPT treatment were made between unstimulated and CPT-treated cells (done in duplicate). Transcriptional activity of the COL1A2/CAT gene in the CPT-free control ('None') was arbitrarily set at 100. Bars show mean ± SEM from 11 independent experiments (*P < 0.01). COL1A2 = type α2(I) collagen; CAT = chloramphenicol acetyltransferase; CPT = camptothecin.