La protein expression promotes proliferation and cell cycle progression of SCC 22B cells.

(A) Lower La expression in siRNA-mediated SCC 22B cells (see Western blot analysis in inlet) correlates with decreased proliferation rate (dotted line). (B) Reduced proliferation rate of La-depleted SCC 22B cells as determined as mean ±SD (error bars) of 5 independent experiments performed in triplicates. P value<0.01 (two asterisks). Two-tailed P value was determined by paired t-test applying Prism 4 (GraphPad Software). (C) SiRNA-mediated depletion of La does not reduce the number of viable cells as determined by counting of trypan blue-negative SCC 22B cells as determined as mean ±SD (error bars) of 3 independent experiments. (D) La depletion (La siRNA) in SCC 22B cells does not induce caspase-3 cleavage of PARP (under apoptosis PARP fragments into 116 and 85 kDa). Representative Western blot analysis of three independent experiments. As positive control PARP cleavage was induced by UV light (lane UV). GAPDH was applied as loading control. (E) SiRNA-mediated depletion of La correlates with a G1 cell cycle arrest in SCC 22B cells (P value<0.05 (one asterisks)). Two-tailed P value was determined by paired t-test applying Prism 4 (GraphPad Software). Error bars represent the mean ±SD of 3 independent experiments. (F) La depletion does not reduce cyclin D1 protein expression in SCC 22B cells. GAPDH was applied as loading control. Representative Western blot analysis of three independent experiments.