KPT-330 treatment increases PP2A activity and downregulates BCR-ABL1 expression and activity. (A) Representative (n = 3) western blot showing BCR-ABL1 activity (anti-PY) and expression (anti-ABL) in vehicle- and KPT-330–treated CD34⁺ CML-BC cells and CD34⁺/CD19⁺ Ph⁺ ALL cells. (B) PP2A activity in 32Dcl3 (positive control), vehicle- and KPT-330–treated (250 nM; 48 hours) 32D-BCR/ABL cells. PP2A activity was normalized to 32Dcl3 cells. (C) Left panel: Graph shows percentage of apoptotic cells (annexin V⁺) in vehicle- or KPT-330–treated (1 µM, 36 hours) parental and small-t–expressing 32D-BCR/ABL cells. Significance was determined using the Student t test of 3 identical experiments. Asterisks indicate P values vs untreated; *P < .05. Right panel: BCR-ABL1 activity (anti-PY) and expression (anti-ABL) in vehicle- and KPT-330 (1 µM, 24 hours)–treated parental and small-t–expressing 32D-BCR/ABL cells. (D) Quantitative reverse-transcription PCR shows BCR-ABL1 mRNA levels in untreated, imatinib (1 µM, 24 hours)–treated, and KPT-330 (1 µM, 24 hours)–treated 32D-BCR/ABL1 cells. (E) Western blot shows effect of KPT-330 (1 µM, 16 hours) on the activity of BCR-ABL1 (anti-PY), STAT5 (anti-pSTAT5^Y694), Akt (anti-pAkt^S473), and p42/44 MAPK (anti-pMAPK^T202/Y204). Heat shock protein 90 was used as a control for equal loading.