As previously performed with AX , we next determined the destabilizing effect of 5b on BCR-ABL1 expression and associated downstream signaling. In K562 cells, 48 h exposure of 5b down-regulated the phospho-BCR-ABL1 and total-BCR-ABL1 levels, as well as the related downstream signaling pathways, as evaluated by immunoblot analysis (Figure ). 5b additionally reduced the expression of client proteins associated with Hsp90 chaperone activity, involving Akt, Stat5, and c-Myc (Figure ).