U2AF1 and cancer: Recent massive sequencing of many cancer genomes allowed the identification of recurrent mutations in genes encoding splicing factors, including SF3B1 (Splicing Factor 3B subunit 1), SRFS2 (Serine and arginine rich splicing factor 2), U2AF1 (U2 small nuclear RNA auxiliary factor 1), and ZRSR2 (Zinc finger CCCH-type, RNA binding motif and Serine/Arginine Rich 2), suggesting that somatic alterations of genes involved in splicing are common in cancer [2,3].