Silencing p21 prevents breast tumor local invasion
and cancer cell migration and invasion. A, Total lysates from parental and shRNA p21 SCP2 cells were analyzed by immunoblotting for the protein levels of p21 and β-tubulin. B, Parental and shRNA p21 SCP2 cells were injected into the mammary glands of four- to six-week-old female Balb/c nude mice. The size of mammary tumor was measured from two sets of mice (eight per group; error bars indicate SEM). C, Representative photographs show hematoxylin and eosin staining of the mammary gland (tumor and fat pad) of 12- to 15-month-old mice. D and E, Transwell cell migration (left panel) and GFR-Matrigel invasion assay (right panel) of parental and shRNA p21 SCP2 cells were performed. Graphs show total migrated and invaded cell number counted by Image J (error bars indicate SEM; n = 3 independent experiments). Student's unpaired t-test was used to compare parental vs. shRNA p21 SCP2 groups. Differences were considered significant at *P < 0.05.