Msr1 affects CML development by regulating PI3K-AKT-GSK-3β pathway and β-Catenin. (A) Msr1 regulates signaling pathways involved in the regulation of LSC functions. Spleens of recipients of BCR-ABL–transduced WT or Msr1^−/− donor bone marrow cells (n = 4) at 14 days after transplantation were collected and protein lysates were prepared for expression of a group of signaling molecules. Loss of Msr1 markedly activated the PI3K-AKT pathway and increased expression of β-Catenin. (B) Quantification of relative protein expression levels in spleens of recipients of BCR-ABL-transduced WT or Msr1^−/− donor bone marrow cells. Mean value (± SD) for each group (n = 4) is shown (P < .05, **P < .01). (C) PMA inhibits PI3K-AKT signaling pathways and β-Catenin expression in human CML cells. K562 cells were treated with PMA, and protein lysates were collected for expression of a group of signaling molecules. PMA markedly inhibits activity of PI3K-AKT and reduced expression of β-Catenin. (D) Over-expression of Msr1 inhibits the PI3K-AKT signaling pathways and reduces β-Catenin expression in human CML cells. Protein lysates from K562 transduced with pMSCV-Msr1-GFP or pMSCV-GFP retrovirus were analyzed by Western blotting for expression of a group of signaling molecules indicated. (E) Msr1 suppresses the proliferation of human leukemic cells. The same number of K562 cells transduced with pMSCV-GFP or pMSCV-Msr1-GFP was cultured in 24-well plates. Live cells were counted at 24h, 48h and 96h (*P < .05, **P < .01). (F) A summary of Msr1 pathway in LSCs of CML.