When compared with Smad3 fl/fl cardiac fibroblasts, FS3KO fibroblasts had significantly lower mRNA expression of Col2a1(C), Col4a1 (G), Col4a2 (I), Thrombospondin-1/Thbs1 (M) and TIMP3 (O), and exhibited trends towards reduced expression of Col1a1 (A), Col3a1 (E) and Col5a1 (K). In contrast, when compared with corresponding Smad2 fl/fl controls, fibroblasts harvested from FS2KO hearts had comparable expression of Col1a1 (B), Col2a1 (D), Col3a1 (F), Col4a1 (H), Col4a2 (J), Col5a1 (L) and TIMP3 (P). Thbs1 levels were significantly reduced in the absence of Smad2 (N). n=4/group. Unpaired t-test.