Cell surface redistribution of CD133 into the uropod of polarized CD34⁺ cells. (A-D) Human CD34⁺ cells, freshly isolated from umbilical cord blood (A,Ci-ii) or cultured for 2 days in the presence of early acting cytokines (B,Di-ii), were labeled with AC133 antibody (anti-CD133; red) and observed by immunofluorescence (Ci,Di). The overlays with the corresponding differential interference contrast images are shown (A-B,Cii,Dii). Note that the cultured CD133^– cells remain small and round (arrows in B), whereas cultured CD133⁺ cells increase in size and CD133 becomes localized into the uropod of polarized cells (B,Di-ii) but remains distributed all over the surface of nonpolarized CD133⁺ cells (arrowheads in B). Same magnification was used in panels A and B (scale bar = 10 μm; A) or in panels Ci and Di (scale bar = 5 μm; Di), respectively.