Normal human lung fibroblasts (NHLFs) were transfected with the indicated siRNA. Cells were labeled with 2,3,3-D3-Serine and treated with TGF-β for 48 hours or left untreated. (A) Analysis of cellular glycine in ALDH1L2 knockdown NHLFs after labeling with 2,3,3-D3-Serine in the presence or absence of TGF-β. (B) Analysis of cellular serine in ALDH1L2 knockdown NHLFs after labeling with 2,3,3-D3-Serine in the presence or absence of TGF-β. (C) Analysis of cellular proline in ALDH1L2 knockdown NHLFs after labeling with 2,3,3-D3-Serine in the presence or absence of TGF-β. (D) Relative levels of media formate content in ALDH1L2 knockdown NHLFs treated with TGF-β or left untreated. (E) Analysis of cellular glycine in MTHFD1L knockdown NHLFs after labeling with 2,3,3-D3-Serine in the presence or absence of TGF-β. (F) Analysis of cellular serine in MTHFD1L knockdown NHLFs after labeling with 2,3,3-D3-Serine in the presence or absence of TGF-β. (G) Analysis of cellular proline in MTHFD1L knockdown NHLFs after labeling with 2,3,3-D3-Serine in the presence or absence of TGF-β. (H) Relative levels of media formate content in MTHFD1L knockdown NHLFs treated with TGF-β or left untreated. (I) Analysis of cellular glycine in ALDH1L2/MTHFD1L knockdown NHLFs after labeling with 2,3,3-D3-Serine in the presence or absence of TGF-β. (J) Analysis of cellular serine in ALDH1L2/MTHFD1L knockdown NHLFs after labeling with 2,3,3-D3-Serine in the presence or absence of TGF-β. (K) Analysis of cellular proline in ALDH1L2/MTHFD1L knockdown NHLFs after labeling with 2,3,3-D3-Serine in the presence or absence of TGF-β. (L) Relative levels of media formate content in ALDH1L2/MTHFD1L knockdown NHLFs treated with TGF-β or left untreated. Bar graphs represent mean ± SEM, n=3. *P<0.05, **P<0.01, ***P<0.001.