RIPK1 and viral infectious disease: While many viruses were shown to trigger both Casp8-mediated apoptosis and RIPK1/RIPK3- or ZBP1/RIPK3-mediated necroptosis [1], the lack of a marker for in situ detection of pMLKL-S345, has rendered it very difficult to truly determine the contribution of necroptotic cell death following viral infection.