NUMB and prostate neoplasm: NUMB exon three and ITGA6 exon 25 (both activated by ESRP2) are predominantly skipped in prostate tumours compared to normal tumour tissue, yet their PSI levels increase in larger, more advanced tumours to produce their respective mRNA isoforms that are associated with a decreased time to biochemical recurrence (Figure 5—figure supplement 2A and B).