COL1A1 and Bloom syndrome: In addition, BLM treatment resulted in a marked increase in the number of GPF-positive, collagen-producing lung fibroblasts in the lung tissue from Col1a1-GFPTg reporter mice, whereas deletion of Txndc5 in Col1a1-GFPTg mice (by crossbreeding Txndc5−/−with Col1a1-GFPTg mice) significantly reduced the number of GFP-positive lung fibroblasts following BLM treatment (Fig. 3d).