Figure 3.

PTBP3 modulates Id1 alternative splicing via binding to its intronic region. (A) Immunoblots showed Id1a and Id1b protein expression levels after altering the PTBP3 expression level in two gastric cancer cells. (B) Western blot analysis of Id1a, Id1b, and PTBP3 expressed in mouse tumors from different PTBP3 knockdown and pSliencer vector-transfected mice. (C) RIP experiments were performed using the PTBP3 antibody to immunoprecipitate (IP) in total-cell extracts of MKN45 cells, and relative enrichment was determined by reverse transcription PCR (upper panel) and quantitative real-time PCR (lower panel). The results are expressed as the mean ± S.D. of three independent experiments. ***P < 0.001. (D) UV cross-linking was performed using 2 pmol 32P-labeled RNA and 50 μg of protein extracts. The immunoprecipitates were subjected to SDS–PAGE followed by autoradiography (upper panel), and the samples were immunoprecipitated with anti-PTBP3 (lower panel). The negative control (Ctr) only has the same amount of protein extracts.