PKB induces adhesion of hematopoietic progenitors to bone marrow–derived stromal cells. (A) CD34⁺ cells, cultured in the presence of SCF and FLT-3L, were retrovirally transduced with myrPKB or eGFP alone. Four days after transduction, hematopoietic progenitors were plated on a confluent layer of bone marrow–derived stromal cells, and an adhesion assay was performed. The percentage of adherent cells was determined by flow cytometric analysis (n = 3). (B) CD34⁺ cells were cultured either in the absence or presence of the PKB inhibitor VIII for 24 or 48 hours, after which time hematopoietic progenitors were plated on a confluent layer of bone marrow–derived stromal cells, and an adhesion assay was performed (n = 3). The percentage of adherent cells was determined by flow cytometric analysis. (C) CD34⁺ cells were cultured either in the absence or presence of the PKB inhibitor VIII for 24 or 48 hours, after which time a transwell migration assay was performed. Human umbilical vein endothelial cells (HUVECs) were plated before the migration experiment on the transwell inserts to obtain a confluent layer of HUVECs. The percentage of migrated cells was determined by flow cytometric analysis (n = 6). Error bars represent SEM. Samples significantly different (P < .05) are indicated with horizontal lines and asterisks.