Figure 1. Multiple functions of STAT5 in BCR-ABL transformed cells. Activation of STATS (1) impacts on cell cycle control (2) enhances anti-apoptotic effects (3) and results in an up-regulation of ROS (4) thereby contributing to an increased mutation rate that contributes to TKI resistance. The enhanced mutation rate is counterbalanced by STATS effects on pro-survival genes such as Bcl-2 and Bcl-XL.