IFNG and melanoma: Indeed, local secretion of lactate by tumor cells within the TME of murine melanoma and pancreatic adenocarcinoma models was associated with less infiltration of NK cells, which produced lower levels of IFNγ and granzyme B. In vitro stimulated NK cells did not only secrete lower levels of IFNγ but also reduced levels of IFNγ transcripts when treated with lactic acid or cultured in low pH conditions.