“…17 It has been shown in human CD34+ cells that expression of FIP1L1-PDGFRA induces cell proliferation and differentiation toward eosinophilic lineage in the absence of cytokines; these effects are mediated by the activation of nuclear factor (NF)-kB and STAT5. 18 Although FIP1L1 is the most common partner of PDG-FRA, five other gene partners have been identified, including BCR, ETV6, KIF5B, STRN, and CDK5RAP2 (reviewed by Gotlib and Cools 14 ). The clinicopathologic features of cases with PDGFRA aberrations other than FIP1L1 have been reported in a very small number of cases and are apparently indistinguishable from those with FIP1L1-PDGFRA.…”