GR-mediated induction of apoptosis in dexamethasone-sensitive ALL. (A) The GR receptor binds to a novel GR promoter of KLF13, activating KLF13 binding to MYB promoter and displacing the MYB activator SP1 (left). KLF13 deactivates MYB expression, decreasing the expression of Bcl2 and allowing BAX to trigger apoptosis. Concurrently, GR also binds a GR promoter in the BIM intronic region (right), increasing BIM expression. BIM binds existing Bcl2, preventing BAX binding and resulting in BAX-mediated apoptosis. (B) Both the GR promoter in KLF13 and the intronic BIM GR promoter are absent in patient-derived leukemia cells resistant to dexamethasone, allowing Bcl2 binding to BAX, resulting in apoptosis inhibition.