Isoform-specific STAT5 loss-of-function phenotypes in TonB cells.

<p>(A) TonB cells were lentivirally transduced with shRNAs targeting control (shGL2), STAT5A/B (shS5A/B), murine STAT5A (sh-muS5A), murine STAT5B (sh-muS5B), and a mixture of both and cultured in the presence of IL-3. Four days after transduction cells were either cultured with IL-3 or switched to BCR-ABL, and the number of viable cells was determined after additional four days by Trypan-blue dye exclusion. The proliferation of non-transduced cells under IL-3 and BCR-ABL was set 100%, respectively. The data represent mean of ten independent experiments. (B) TonB cells transduced with isoform-specific anti-STAT5 shRNAs were cultured four days in the presence of IL-3 or BCR-ABL. Protein expression of BCL-X_L and BCL-2 was analysed by western blotting. Expression of ERK2 served as loading control. The numbers indicate changes in protein expression in % as determined by densitometry. (C) TonB cells lentivirally transduced with isoform specific STAT5 shRNAs were cultured in the presence of IL-3 or doxycycline as described in (B). mRNA expression was quantified by qRT-PCR. BCL-X_L expression was normalized to HPRT mRNA-expression, and GL2-ctrl was set as 100%. The data represent mean ± SE of four independent experiments.