TGM1 and metastatic melanoma: In Li et al. study, by analyzing the DEGs between metastatic and nonmetastatic melanoma and constructing the protein-protein interaction (PPI) network, it was found that as proof of the differential expression of metastasis-associated genes, 11 keratinocyte differentiation-involved genes, including LOR, EVPL, SPRR1A, FLG, SPRR1B, SPRR2B, TGM1, DSP, CSTA, CDSN, and IVL, were down-regulated in metastatic melanoma in comparison with primary melanoma based on the data from TCGA [39].