Structures of the mutant EPO R/ABL chimeric proteins. The EPO R/ABL constructs used in this study are summarized. ▵ABD, actin-binding domain (c-terminal 167 amino acids) deletion; ▵SH2, Src-homology domain 2 deletion; ▵SH3, Src-homology domain 3 deletion; KD, kinase dead has a point mutation at K290M. The location of the chimeric receptor proteins is indicated by an arrow.