Impaired experimental skin wound healing in discoidin domain receptor 2 (DDR2)-/- mice correlates with defective fibroblast recruitment and MMP2 activity. (a) Impaired experimental skin wound healing in discoidin domain receptor 2 (DDR2)-/- mice. Following experimental wounding, the area of the remaining wound was measured using a caliper (n = 12). *P < 0.001, and #P < 0.05, significantly different compared with DDR2+/+ group. (b) Representative western blot analysis of α smooth muscle actin (αSMA) expression in skin tissue extracts from three DDR2-/- and three DDR2+/+ mice, wounded 7 days before. Tubulin expression was used as control for protein loading. Bands were semiquantified by scanning densitometry and results expressed as a ratio αSMA/tubulin to reflect average density of fibroblast per wound. (c) Representative gelatin zymography in DDR2-/- and DDR2+/+ skin tissue extracts wounded 7 days before. Bands from pro-matrix metalloproteinase (MMP2) and MMP2 were semiquantified by scanning densitometry. Total MMP2 activity in DDR2-/- expressed relative to that of DDR2+/+.