Despite these limitations, the efficacy of JAK2 inhibitors has been demonstrated in several pre-clinical models of JAK2-mutant (Bercovich et al., 2008; Mullighan et al., 2009c; Yoda et al., 2010; Tasian et al., 2012; Van Bodegom et al., 2012; Wu et al., 2015; Steeghs et al., 2017) and JAK2r (Maude et al., 2012; Chase et al., 2013; Boer and den Boer, 2017; Downes et al., 2021) ALL. Here, JAK2 is linked to acute lymphoblastic leukemia.