The constitutive expression of a dominant negative Stat5A mutant interferes with the growth factor independence conferred by the TEL-Jak2 fusion in Ba/F3 cells.

Ba/F3 cells constitutively expressing the pRSVNeo-Stat5AΔ749 vector (Stat5AΔ749) were stably transfected with TEL-Jak2 (Stat5AΔ749+TEL-Jak2) or the empty expression vector (Stat5AΔ749+pBabePuro). As a control, the parental pRSVNeo Ba/F3 cells were stably transfected by TEL-Jak2 (Neo+TEL-Jak2). The proliferation rates of the indicated Ba/F3 cell lines were scored daily for 8 days in either the presence (A) or absence (B) of WEHI conditioned medium.