PRPF4 and Ewing sarcoma: Through the splicing mechanism, PRPF4, SRSF1, and HNRNPM regulate the cell proliferation, migration, and invasion in different cancers, including lung cancer (Choi, 2012; Chang and Lin, 2019), breast cancer (Anczuków et al., 2015; Sun et al., 2017; Park et al., 2019), cutaneous squamous cell carcinoma (Zhang et al., 2018), hepatocellular carcinoma (Tu et al., 2019), esophagus dysplasia (Varghese et al., 2015; Fitzgerald et al., 2018), gastric cancer (Wu et al., 2019), cervical cancer (Dong et al., 2019), and Ewing's sarcoma (Passacantilli et al., 2017).