PYCR1 and cancer: ALDH18A1 protein levels and PYCR1 mRNA have also been shown as upregulated in cancer-associated fibroblasts (CAFs), and silencing of these enzymes perturbed collagen formation, in particular collagen type I, α1 (COL1A1)—a crucial extracellular matrix (ECM) component (Kay et al. 2020) (Fig. 3A).