Fibroblasts internalize collagen independently of uPARAP in vivo. (A) Percentage of collagen-internalizing GFP-positive and GFP-negative cells in the dermis of collagen- and dextran-injected Mrc2^+/+ (wild type; n = 4) and Mrc2^−/− (n = 6) mice. *, P < 0.01, Student’s t test, two tailed. Data are shown as means ± SD. (B and C) Representative high-magnification images of the dermis of collagen-injected Col1a1-GFP transgenic Mrc2^+/+ (B) and Col1a1-GFP transgenic Mrc2^−/− (C) mice. Examples of endocytic vesicles containing collagen and dextran are indicated with arrows. Bars, 10 µm.