For example, frequent heterozygous somatic missense mutations in SRSF2, SF3B1, ZRSR2 and U2AF1 have been identified in many cancers, especially in certain subtypes of leukaemia (Wang et al., 2011; Yoshida et al., 2011; Graubert et al., 2012; Yoshida and Ogawa, 2014; Anczuków and Krainer, 2016; Wang and Aifantis, 2020). Here, U2AF1 is linked to cancer.