RIPK1 and infection: Examining changes in RIPK1 over the course of MDM infection in vitro, we found an upregulation of full length RIPK1 at day 2 post-infection until day 8 post-infection (Fig. 7a) that was associated with a gradual and significant accumulation of cleaved RIPK1 on days 2, 4, 6 and 8 post-infections (Fig. 7a).