Internalization of CXCR4 after exposure to SDF-1α.

Internalization of CXCR4 was analyzed by confocal laser scanning microscopy in HPCs. (A) Untreated cells. (B) Cells after exposure to 1 μg/mL of SDF-1α for 30 minutes. (C) Cells after exposure to 1 μg/mL of SDF-1α for 1 hour. (D-I) Double immunofluorescence for CXCR4 (green) and CD41 (red) on day 3 cells, cultured in the presence of SDF-1 (D-F), compared with control cells (G-I). The yellow area in panel I indicates the colocalization of both the receptors on the membrane (bar = 10 μm).