TGM2 and chronic kidney disease: Given the strong association of kidney TG2 and ε-(γ-glutamyl)-lysine crosslinking with experimental [33, 41] and human CKD [39, 42], coupled with the highly effective anti-fibrotic effects of TG2 inhibition observed in pre-clinical models [43, 44], we hypothesized that urine and circulating levels of TG2 and its crosslink product, ε-(γ-glutamyl)-lysine, may provide a novel non-invasive way of assessing the rate of fibrotic remodeling and thus CKD progression.