Imatinib mesylate inhibits collagen synthesis in human breast stromal fibroblasts. Imatinib mesylate inhibits collagen synthesis in human breast stromal fibroblasts. A. Confluent breast fibroblast cultures, arrested in DMEM containing 0.2% FCS in the presence of tritiated proline (5 μCi/mL), were treated with 10 μmol/L imatinib. Forty-eight hours later, collagen synthesis was estimated as described in Materials and Methods. Columns, average of eight separate experiments. B. Confluent breast fibroblast cultures, arrested in DMEM containing 0.2% FCS, were treated with 10 μmol/L imatinib. Cell lysates were collected at 6 and 24 h later in the absence (C6 and C24, respectively) or presence (I6 and I24, respectively) of imatinib, and RNA was isolated and subjected to real-time PCR, as described in Materials and Methods. Columns, average of three separate experiments. *, P < 0.05; **, P < 0.01. Vassiliki Gioni et al. Mol Cancer Res 2008;6:706-714 ©2008 by American Association for Cancer Research