β-Arrestin-1 antibody validation and migratory propensity of breast cancer cells (MDA-MB-468 and MDA-MB-231 cell lines) after β-arrestin-1 overexpression and silencing. A: β-Arrestin-1 overexpression was detected with anti-GFP antibody on Western blot, 48 hours after transfection. V, vector. B: Protein expression was significantly decreased 48 hours after transfection with siRNA against β-arrestin-1 in both cell lines, analyzed by immunocytochemistry. Magnification ×40. C: Overexpression of β-arrestin-1 reduced migration of both cell lines, compared with control, 48 hours after transfection. *P < 0.001; **P < 0.001. D: Knockdown of β-arrestin-1 resulted in an increased migratory propensity of both cell lines, compared with control, 48 hours after transfection. *P < 0.001; **P < 0.001.