FAS and Sepsis: This progressive depletion is greater in memory B cells than in naïve B cells, suggesting that the reduction in number is not the result of impaired bone marrow generation but sepsis-induced apoptosis, which may be associated with higher phosphorylation of ERK, an intracellular kinase related to transition to apoptosis, and increased expression of CD95, a cell-death receptor [158, 209].