Figure 1.

Growth factors induce p21 and inhibit proliferation in bladder carcinoma cells. UMUC-3 and UMUC-14 human urothelial carcinoma cell lines were serum starved for 24 hours and then stimulated with growth factors. (A) Cells were lysed at intervals after addition of 10 ng/ml EGF, and proteins were harvested for immunoblotting against p21 and α-tubulin. Quantitation of relative p21 signal normalized to tubulin after 180 minute EGF treatment is shown in the graphs. There were 4 replicates of each treatment for the UMUC-3 cells and 3 replicates of the UMUC-14 cells. Error bars represent S.E.M. (B) UMUC-3 cells were treated with varying concentrations of PDGF for 90 minutes and then were harvested. Lysates were immunoblotted for expression of p21 and phosphorylation levels of AKT at serine 473. Relative levels of p21 normalized to tubulin after 90 minutes of 100 ng/ml PDGF treatment is shown in the graphs for both UMUC-3 and UMUC-14 cells. There were 4 replicates of each treatment. (C) UMUC-3 cells were transfected with control or p21 siRNA and 48 hours later, cells were serum starved for 24 hours. Then 10 ng/ml EGF was added to half of the wells and 24 hours later an MTS assay was run. * significantly different from all other treatments, p = .002.