In contrast, we observed that the KIR2DL4 protein expression was lacking in the human neoplastic mast cell line HMC1.2 expressing mutated KIT and deficient in FcεRI expression [52], and that nine of 15 cutaneous mastocytosis samples were KIR2DL4-negative [30]. This evidence concerns the gene KIR2DL4 and mastocytosis.