COL3A1 and obesity due to melanocortin 4 receptor deficiency: We identified several significant differences in the expression levels of genes involved in ECM organization, among them App, Bcl3, Col3a1, Ctgf, Ctss, Cyr61, Lcp1, Lgals3, and Lox. Obese mice usually showed lower expression levels and lower numbers of ECM-associated cells, a stiffer and excessive ECM with an impaired signaling cascade when compared to normal weight individuals, whereas nutritional cues present in obesity are also of note due to their influence on increased free fatty acids (Garg et al., 2015; Lin et al., 2016; Chapman et al., 2017; Werner et al., 2018).