SRPK1 (serine-arginine protein kinase 1) overexpression deregulates alternative splicing and promotes cancer through distinct oncogenic processes such as angiogenesis and apoptosis. (a) SRPK1 overexpression switches VEGF (vascular endothelial growth factor) alternative splicing towards the proangiogenic VEGF isoform(s) in prostate cancer, colorectal cancer, melanoma, and tumor endothelium. (b) SRPK1 overexpression switches IR (insulin receptor) and MCL-1 (myeloid cell leukemia-1) alternative splicing towards the antiapoptotic isoforms IR-A and MCL-1L, respectively, in hormone-positive breast cancer.