Corresponding to the magnitudes of cell death observed in Oasl1+/+ and Oasl1–/– fibroblasts (Fig. 1c), MCMV-M45mutRHIM infection-induced RIPK3 phosphorylation was drastically reduced in Oasl1–/– fibroblasts compared with Oasl1+/+ fibroblasts (Fig. 1f, left). Here, RIPK3 is linked to infection.