The article by Ohsaki et al. proposed a novel mechanism of cytokine production in γ-irradiated cells. γ-Ray irradiation induced sustained IL-6 production in HaCaT epidermal cells from 33 h after irradiation. Extracellular ATP-induced activation of P2Y11 receptor was involved in the production of IL-6. At the downstream of P2Y11 receptor activation, the p38 MAPK and NF-kB signaling was involved in IL-6 production. The protein level of G9a, which inhibits IL-6 production, was decreased after g-irradiation. These findings should be helpful to understand the pathogenesis of radiation-induced inflammation, as well as the potential side effects of therapeutic irradiation.