COL1A1 and metabolic dysfunction-associated steatohepatitis: Consistent with the histopathology scoring, gene expression of α-1 type I collagen (Col1a1), the major component of fibrillar collagen in the liver, the profibrogenic cytokine transforming-growth factor-1 (Tgfb1) and tissue inhibitor of metalloproteinases 1 (Timp1), which inhibits matrix degradation, was increased in the four NASH susceptible strains (A/J, BL6, CBA and FVB/N–Timp1 in FVB p = 0.065) but not in the NASH resistant mouse strains, except for a significant increase in Timp1 gene expression in C3H mice with NASH (Fig. 2A–C).