Reduced tensile strength of discoidin domain receptor 2 (DDR2)-/- wounds. (a) Representative histogram of tensile mechanical testing in DDR2-/- and DDR2+/+ wounded skins (n = 6). Results are expressed as maximal load to failure (g). (b) Representative colorimetrical analysis of acid-soluble collagen amounts in skin lysates (n = 6) 7 days after wounding. Wounds were homogenized in lysis buffer and clarified by centrifugation. Total soluble collagen was measured colorimetrically at 540 nm using the Sircol Collagen Assay kit. *P < 0.001, significantly different compared with DDR2+/+ group.