Interruption of BDNF-induced cell invasion by TrkB-siRNA. In TrkB-siRNA transfected A549 cells, the decreased activity of Pyk2 in Tyr402 promoted by BDNF was detected, which was much lower than that in non-silencing siRNA transfected and control cells. The activation of ERK was also attenuated after TrkB silencing (A). The invasion of TrkB-siRNA transfected A549 cells was greatly inhibited, in comparison to those non-silencing and control cells (B). Original magnification, all ×400. The data are representative of three individual experiments.