HMVEC were transfected with siRNAs for ERK1, ERK2, or both ERK1 and ERK2 for 24 hours, and then treated with LPS (1 μg/ml). (A) Expression of total ERK1/2 after siRNA transfection by western blotting. Relative density of ERK1/2 was compared to that of β-actin. (B) IL-6 levels in supernatants of LPS-treated HMVEC that had undergone siRNA knockdown of ERK1, ERK2, or both ERK1 and ERK2. n = 4; *p≤0.05; NS, not significant.