TGM2 and head and neck squamous cell carcinoma: As for the HNSCC cell lines UM-SCC19 and UM-SCC47, they showed the opposite effect by downregulating the expression of CLEC3B and CCRL1 in the PFs (*** p < 0.001) after tumor cell-fibroblast co-culturing while not affecting the RF marker expression of TGM2 and MGP in the RFs.