PRF1 and cancer: Several studies have underlined the critical and distinct roles for γδ T cells, and αβ T cells (Girardi et al., 2003), as well as NK and NKT cells, in immunosurveillance against cancer (Smyth et al., 2000; Dunn et al., 2004) in which interferon-γ (IFN-γ), perforin, and IFN-α/β represent key factors involved in triggering cancer cell death (Smyth et al., 2000; Dunn et al., 2004).