TGFB1 and neoplasm: A majority of the peptide reactive CD8+ cells may not be tumor reactive due to various mechanisms such as down modulation of HLA class I on tumor cell surface and presence of regulatory T cells and TGFβ, etc. Sorting of the tetramer positive cells for generation of CTL in vitro has been used as adoptive transfer (cell based therapy) in melanoma patients [21,22].