MMP1 and Insulin resistance: Interestingly, a significant elevation in Toll-like receptor-2 (TLR2) expression, a sensor of saturated fatty acids that elicit inflammatory responses promoting insulin resistance (see review [51]), was also observed under a HFD, while Tlr2−/− mice fed with a HFD had decreased levels of Col1a1, Col1a2, and TIMP1 but increased MMP1 transcripts compared with WT fed the same diet [94].