RIPK1 and viral infectious disease: Recent studies have reported that RIPK1 kinase activity is not universally required for all necroptosis instances, as RIPK3 can be activated independently of RIPK1 by external stimuli, such as viral infection, heatstroke, and osmotic stress, which activate RIPK3 via Z-DNA-binding protein 1 (ZBP1) [23, 26, 44, 45].