SPARC and central nervous system cancer: SPARC not only increases the synthesis of collagen I,24 but also regulates the processing of procollagen I and collagen in dermal fibroblasts.40 Therefore, to assess changes in matrix production, processing and fibrillogenesis because of SPARC expression, control- (−SPARC) and SPARC (+SPARC)-expressing U87 glioma cells (Fig. 1a) were implanted into nude rat brains, and Day 7 control and SPARC-expressing tumors were obtained (Fig. 1b).