U2AF1 and cancer: Other splicing inhibitors such as sudemycin D6 or E7107 also display stronger cytotoxic effects on splicing factor–mutant cancer cells, including mutations in SF3B1 and other splicing factors such as U2AF1 (Shirai et al, 2017) and SRSF2 (Lee et al, 2016; Obeng et al, 2016).