SERP2 (stress associated endoplasmic reticulum protein family member 2) functions as a serine proteinase inhibitor (serpin) with critical roles in viral pathogenesis and cellular stress responses. The protein primarily inhibits caspases and granzyme B, though with varying efficacy compared to related serpins like CrmA 1. SERP2 demonstrates weak inhibitory activity against interleukin-1β-converting enzyme (ICE/caspase-1) with a Ki of 80 nM and granzyme B with a Ki of 420 nM 1. The protein's mechanism involves proteinase inhibition through its reactive site loop containing aspartate at the P1 position, though it forms less stable complexes with target proteases compared to other serpins 1. SERP2 plays crucial roles in preventing apoptosis and controlling inflammatory responses during viral infections 2. Mutation studies reveal that the P1-site aspartate is essential for proteinase inhibition, and alterations cause increased apoptosis in cultured cells 3. In cancer research, SERP2 has emerged as a potential biomarker, with differential expression patterns identified in colon cancer recurrence studies 4. The protein's anti-apoptotic properties have also been exploited in oncolytic virus therapy applications for cancer treatment 56.