DDR2 was knocked down in non-differentiating primary rat osteoblasts using shRNA lentivirus technology with a different shRNA from what was used in experiments with mouse osteoblasts (see Methods). Transduced cells were differentiating for seven days, serum starved and then treated with control collagen (0.2 mg/ml) for 24 hours. Cell layer protein was extracted and subjected to Western blotting for 50 kDa pro-lysyl oxidase, mature 32 kDa lysyl oxidase and β-actin (loading control). (A) Western blot showing 70% knockdown of DDR2 on day 7 of differentiation in knockdown cells; (B) Western blots for pro- and mature lysyl oxidase protein and quantitation. Data (means +/− SD) are from one of two experiments each performed in triplicate with the same outcome (n = 3; *, p<0.05, N.S., not significant; ANOVA with Tukey post-hoc).