TGM2 and melanoma: TG2 stabilized contact points of tumor cells with the subendothelial matrix in free-floating melanoma cells isolated from arterioles.144 In contrast, the downregulation of TG2 expression in melanoma cancer cells promoted their ability to metastasize.145 The ectopic expression of TG2 in a highly malignant hamster fibrosarcoma cell line significantly reduces tumor incidence despite the fact that TG2-transfected clones exhibit no significant differences in growth rates, cell morphology, or levels of spontaneous apoptosis in vitro.