Figure 1. IGF-I decreases long-term viability of human fibroblasts.
Long-term IGF-I treatment reduces colony formation potential. Colony forming assays were performed on cells that had been maintained in either MCDB 105 medium without additions or with IGF-I (40 ng/ml) for 2 weeks. Cells were seeded in full growth medium to allow colony growth and results are presented in panel A. Bars are number of colonies per 3×103 cells plated (*, P<0.01) B. Representative micrograph (20X) of senescence-associated β-galactosidase staining of fibroblast colonies. C. Crystal violet stained colonies of plates seeded with 3×103 cells for colony forming assays.