PRF1 and neoplasm: IL-17 was the signature cytokine of Th17; researches showed that IL-17 could enhance the cytotoxic effects of NK cells against tumor cells by augmenting the expression of cytotoxic molecules including tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), Perforin, and Granzyme B [31].