Fig. 1. N-cadherin expression regulates migration of OSCC cells. (A) Tert-immortalized oral keratinocytes (OKF4 and OKF6) and malignant OSCC cells (SCC9, SCC25, SCC68 and UMSCC1) were serum-starved overnight, and E- and N-cadherin expression was then determined by western blot analysis. Using real-time PCR the relative mRNA expression of E-cadherin, N-cadherin and GAPDH was determined, and normalized to the level of E-cadherin in SCC9 cells and the level of N-cadherin in OKF4 cells. (B) SCC9 and SCC25 cells were transfected with 100 nM of control siRNA (siCtrl) or 1:1 mixture of two N-cadherin-specific siRNAs at 50 nM each (siNcad); E-cadherin, N-cadherin and ERK protein levels were determined 72 hours later by western blot analysis. Using real-time PCR the relative expression of E-cadherin, N-cadherin and GAPDH was determined and normalized to siCtrl-transfected cells. (C) SCC9 and SCC25 cells were transfected with siCtrl or siNcad, and 48 hours following transfection cells were added to porous polycarbonate filters that had been coated with 5 µg type I collagen. Cells were allowed to migrate for 24 hours, nonmigratory cells were removed from the upper chamber and migrating cells counted. ^*P<0.05, significantly different from siCtrl-transfected cells. Results are representative of at least three independent experiments.