ERK1/2 and NF-κB signaling have been implicated in the regulatory control of the balance between the pro-apoptotic protein Bax and the antiapoptotic protein MCL-1, the relative levels of which are crucial for the onset of constitutive neutrophil apoptosis (54), and Western blotting for these two proteins revealed stabilization of MCL-1 in response to HCMV infection but no change in Bax expression levels (Figure 4F). Here, PROS1 is linked to cytomegalovirus infection.