STAG2 and Ewing sarcoma: Indeed, cohesin or its regulators are frequently mutated in different types of tumors such as colorectal cancer (NIPBL) (Barber et al., 2008), glioblastoma, Ewing’s sarcoma, urothelial bladder carcinoma, melanoma (STAG2) (Solomon et al., 2011, 2013; Balbás-Martínez et al., 2013) and myeloid neoplasms (STAG1, STAG2, SMC3, and RAD21) (Dolnik et al., 2012; Kon et al., 2013).