TI - Phosphorylation of Bax Ser184 by Akt regulates its activity and apoptosis in neutrophils . AB - Although important for apoptosis , the mechanism of Bax regulation is poorly understood . This study demonstrates that phosphorylation of Ser(184) regulates Bax activity . The phosphorylation required phosphatidylinositol 3-kinase/Akt activation and appeared to be mediated by Akt itself . In the serine-phosphorylated form , Bax was detected in the cytoplasm , could not be immunoprecipitated with the activation-specific antibody 6A7 , and promoted heterodimerization with Mcl-1 , Bcl-x(L) , and A1 . Apoptotic neutrophils possessed reduced levels of serine-phosphorylated Bax correlating with an increase in activated Bax as well as an increase in the amount of Bax found translocated to the mitochondria . We suggest that Bax is regulated by phosphorylation of Ser(184) in an Akt -dependent manner and that phosphorylation inhibits Bax effects on the mitochondria by maintaining the protein in the cytoplasm , heterodimerized with antiapoptotic Bcl-2 family members .