Normal human lung fibroblast (NHLF) migration through collagen I and collagen IV is discoidin domain receptor (DDR)2-dependent. NHLFs were reverse transfected with negative control small interfering (si)RNA, or specific siRNA for DDR2, DDR1 (A, C), Janus kinase (JAK)2, or extracellular signal-regulated kinase (ERK)1/2 (B, D) using lipofectamine RNAiMAX. At 48 h after transfection, NHLFs were serum-starved for 24 h and transferred to 8.0 μm polycarbonate inserts coated with collagen I (10 μg/cm2) (A, B) or collagen IV (10 μg/cm2) (C, D). Where indicated, cells were incubated with collagen I (25 μg/mL) or vehicle (acetic acid, 0.1 M) for an additional 16 h (E). The bottom chamber was treated with cell dissociation buffer and acetomethoxycalcein (calcein AM) for 1 h at 37°C. The fluorescence of solution with detached cells was measured at 485 nm excitation and 520 nm emission. Results are representative of mean fold increase ± SD of two independent experiments performed in triplicate (n = 6, *P < 0.05, **P < 0.01).