Figure 6.

Increased proliferative potential and decreased differentiation in the presence of PI 3-kinase or mTOR inhibitors. Starting near confluence, SIK cultures were treated with 2 µM arsenite, 10 µM LY294002, 5 nM rapamycin or co-treated with arsenite and LY294002 or rapamycin. (A) Fold increases in CFE are given after 7 days relative to those of untreated cultures (absolute values 1.9 + 0.9%), indicated by the dotted line. The results (mean ± SD) are representative of five independent experiments. Except for cultures treated with rapamycin alone, values are significantly different from untreated (*p < 0.02). (B) mRNA expression of involucrin, keratin 1, keratin 10, and TGM1 was measured using real-time PCR after 3 days of treatment and is presented relative to untreated, set as 1. Averages are given of 3–7 independent experiments, where significant differences from untreated for each differentiation marker are indicated by the asterisk (p < 0.001 for each marker). (C) PKCδ levels in particulate and soluble fractions were determined after 7 days of treatment. In parallel, Tyr 311 phosphorylation (pTyr 311) in total cell lysates was measured. β-Actin is used as a loading control. Data are representative of three independent experiments.