CASP1 and melanoma: Absent in melanoma 2 (AIM2) is originally identified as a tumor suppressor of melanoma and named absent in melanoma 2.1 AIM2 is a member of the interferon (IFN)-inducible PYHIN protein family.2 In immune cells, AIM2 is mainly observed in innate immune cells, such as macrophages and dendritic cells, and functions to sense pathogen-associated or host-derived cytosolic dsDNA, recruit other inflammasome components, such as ASC and pro-caspase-1, and induce caspase-dependent inflammasome formation.