Suppression of BDNF-induced cell invasion by PD98059. The inhibited phosphorylation of ERK was observed after PD98059 treatment (A). The invasion of PD98059 treated A549 cells was diminished accordingly, compared with those non-silencing and control cells (B). It was indicated that the activated ERK was essential for regulating the invasion of A549 cells induced by BDNF. Original magnification, all ×400. The results are representative of three independent experiments.