TGFB1 and pulmonary fibrosis: We therefore chose to use the mouse fibroblast cell line, NIH3T3, due to: 1) the ability to efficiently express semaphorin-7A by transient transfection, 2) the low basal expression of semaphorin-7A so as to allow us to compare the effects of overexpression of semaphorin-7A, and 3) the responsiveness of this cell line to TGF-β and the established use of this cell line in evaluating molecular mechanisms involved in pulmonary fibrosis [31–35].