Cotreatment with PS inhibits SDF-1α-mediated internalization of CXCR4 in AML cells. (A) OCI-AML3 cells were treated with 100nM SDF-1α for the indicated times. After SDF-1α stimulation, cells were collected and surface expression of CXCR4 was assessed by staining the cells with anti-CXCR4 12G5 antibody and flow cytometry. (B) OCI-AML3 cells were treated with the indicated concentrations of PS for 24 hours followed by stimulation with 100nM SDF-1α for 15 minutes. Then, cells were collected and surface expression of CXCR4 was assessed by staining the cells with anti-CXCR4 (12G5) antibody and flow cytometry. (C) Immunoblot analyses of pAKT, AKT, pERK1/2, ERK1/2, CXCR4, GRK3, and hsp70 in total cell lysates from OCI-AML3 cells treated with the indicated concentrations of PS for 24 hours followed by stimulation with SDF-1α for 15 minutes. The expression of β-actin in the lysates served as the loading control.