TGFB1 and neoplasm: Others have also identified tumor-derived PGE2 and TGFβ as being capable of inducing a CD11cloCD11bhi arginase-expressing DC subset which impairs T cell activation, while additional studies have defined a CD11chiCD11b+MHC II+ DC population that inhibits CD8+ T cell responses in several murine tumor models in an arginase-dependent manner (33, 34).