SRSF2 and SRSF6 promote longer isoform of Bcl-x alternative splicing. (A) Schematic of alternative 5’ splice-site selection in Bcl-x pre-mRNA is shown. Exons are shown with boxes. Introns are shown with lines. Location of 5’ splice-sites of longer (5’L) and shorter (5’S) isoforms are shown. Primers used in endogenous RT-PCR are shown by arrows. (B) Schematic of Bcl-x minigene is shown. Deleted intron length is shown. Sequences from vector are shown as dotted arc. Primers used in RT-PCR are shown with arrows. (C) RT-PCR assays of 5’ splice-site selection in Bcl-x pre-mRNA within Bcl-x minigene in pcDNA (3.1), SRSF2, SRSF3, SRSF4, SRSF5, SRSF6, SRSF7, SRSF9, Tra2β and U2AF65 overexpressed cells are shown. Quantitation results are also shown. (D) RT-PCR analysis of Bcl-x alternative splicing in SRSF2 or SRSF6 knockdown, untreated or non-silencing shRNA treated 293T cells are shown.