It has been reported that HtrA2/Omi can mediate caspase-independent PCD via its serine protease activity, e.g. upon interleukin-3 deprivation of the mouse pro-B cell line Ba/F3[25], in imatinib-treated human leukemic cells[26], or in cytomegalovirus infection[27]. Here, HTRA2 is linked to cytomegalovirus infection.