To begin addressing these questions, we investigated whether other tumor suppressor genes (TSGs) also show evidence of pPA events following large internal exons like MAGI3. Using public mRNA isoform expression databases to survey fifty TSGs from the Cancer Gene Census13, we found that twenty of them harbor at least one large internal exon (defined as >500 nt) (Supplementary Table S1). The gene discussed is MAGI3; the disease is cancer.