BDNF-directed migration and invasion of human chondrosarcoma cells involves up-regulation of matrix metalloproteinase-1 (MMP-1). (A) JJ012 cells were incubated with BDNF (50 ng/mL) for 24 h, and the mRNA levels of MMP-1, -2, -3, -9, and -13 were determined using qPCR; (B) JJ012 cells were incubated with BDNF (50 ng/mL) for indicated time intervals, and the protein and mRNA expressions of MMP-1 were examined by western blotting and qPCR; (C and D) JJ012 cells were incubated with various concentrations of BDNF (30–100 ng/mL) for 24 h, and MMP-1 expression was examined based on enzyme-linked immunosorbent assay (ELISA) and MMP-1 promoter activity; (E and F) Cells were transfected with MMP-1 siRNA for 24 h followed by treatment with BDNF (50 ng/mL) for 24 h, and cell migration and invasion were examined using the Transwell assay. Results are expressed as the mean ± S.E. *p < 0.05 compared with control; #p < 0.05 compared with BDNF-treated group.