This sentiment was echoed by another study which demonstrated that in vitro, highly suppressive Tr1 cells were generated from CD4+CD25− T cells in the presence of autologous DCs and irradiated COX-2+ HNSCC cells or exogenous PGE2, with a cytokine cocktail that included IL-10 (29). This evidence concerns the gene PTGS2 and head and neck squamous cell carcinoma.