MMP12 and obesity due to melanocortin 4 receptor deficiency: However, in two animal models of genetic obesity (ob/ob and db/db) and in a HFD model, while mRNA levels for MMP2, MMP3, MMP12, MMP14, MMP19, and TIMP1 are robustly induced, MMP7 (and MMP3) transcripts are markedly reduced in obese visceral adipose tissue compared to lean tissue [31].