CD4 and serum lipopolysaccharide activity: We observed significantly fewer CD4+CD8+ double‐positive (DP) thymocytes in the thymus of the Panx1−/‐ mice than in the WT mice after LPS stimulation (Figure S2J,K), suggesting that Panx1 deficiency leads to more serious thymic involution in a mouse model of endotoxemia.40