Given the complex multicellular events that mediate tumour growth within specific microenvironmental niches, the processes leading to the formation of the metastatic niche are only beginning to be understood, and there is evidence of a key role for TG2 in these processes; with studies suggesting a pro- and anti-metastatic functions through differential expression in metastatic cancers, cell lines, and consequences of inhibition in animal models across a range of cancer types [17,47,134,209,210,241,242,243,244]. Here, TGM2 is linked to cancer.