The migration of PC-3 sphere cells was gradually enhanced in differentiation. A, The migration capacity of PC-3 sphere cells and adherent cells was analyzed by transwell assays. Five predetermined fields were photographed at 200x magnification, and cells were counted and analyzed with a histogram (31.5 ± 3.5 versus 122.0 ± 12.5, Student’s t test). B, The migration capacity of re-cultured sphere cells on days 1, 2, 3, and 4 was tested by transwell assays. (ANOVA) **p < 0.01.