STAT1 and cancer: Animals that possess naturally occurring or experimentally induced defects leading to loss of recombination-activating gene 2 (RAG2), αβ T cells, γδ T cells, invariant NKT cells, interferon-γ (IFNγ) receptor 1 (1); signal transducer and activator of transcription 1 (STAT1), perforin; or tumor-necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) (2) are more susceptible to spontaneous development of cancer or carcinogenic stimuli.