Targeting a conditional SB allele to the hematopoietic system in mice expressing the constitutively active JAK2V617F resulted in a strong phenotypic selection for an erythroleukemia-like disease.86 The vast majority of SB/JAK2V617F mice developed an aggressive erythroleukemia occasionally coincident with CD4+/CD8+ T-cell ALL. Here, CD4 is linked to erythroleukemia.