The effect of chemotherapy drugs on the expression and function of CD44. (A) Leukemia cells treated as described above were incubated with fibrinogen (Fbg) for 2 hours. Fluorescence images were observed by using confocal microscopy. Each image is from at least 3 experiments. Scale bar, 20 µm. (B) The MFI of Fbg on the surface of leukemic cells was measured by using ImageJ. (C) Western blotting was used to measure CD44 protein expression levels. The fold change was calculated by using ImageJ and compared with the data in the APL/NB4-only group. (D-E) APL/NB4 cells were treated as previously described, and the expression level of the PI3K pathway was studied. The data in the APL-only group were regarded as the baseline. (F) The expression of CD44 in the presence of ATO with/without the PI3K agonist 740-YP (20 µM/L). *P < .05, **P < .01 in panels C, E, and F. *P < .05 vs the empty group in panel B. DAPI, 4′,6-diamidino-2-phenylindole; ns, not significant.