Fig. 6. Effect of PC inhibitors on IGF-1 receptor pathway. (A) Confluent 3T3-L1 preadipocyte cells treated or not with dec-RVKR-CMK (100 µM) for 48 hours (lanes 1,2) as well as control and 1-PDX cells (lanes 3,4) were analyzed by immunoblot for proIGF-1R processing. The arrowhead points to an unknown immuno-crossreactive protein that was unaffected by the inhibitor. (B) IRS-1 phosphorylation was analyzed by sequential probing of a blot carrying proteins from control and 1-PDX cells, stimulated or not with insulin (10 µg/ml). The first probing was conducted with an anti-IRS-1 antibody and the second probing was conducted with an anti-phosphotyrosine antibody. (C) Effect on mitotic clonal expansion. Control and 1-PDX cells were induced or not to differentiate. After 3 days, cells from 6-well culture dishes were trypsinized and cell number was determined by counting. Data shown are the means±s.e. Results are representative of three independent experiments with three individual clones of each cell lines.