Mode C depicts the role of protein modifications (e.g., phosphorylation). A viral protein can either mimic the host modifications (Figure 7, marked C1) . Alternatively, a modification occurs by a viral enzyme (Figure 7 , marked C3). Such mimicry can lead to a modification of the original site or at an entirely new site (Figure 7, marked C2) . Apparently, there are instances in which both the modifying enzyme and the target proteins are both sequences that were acquired from the host (Figure 7, marked C4) . This mode is dependent on the presence of active kinases (or phosphatases). For example, human cytomegalovirus (HCMV) kinase introduces phosphorylation sites that perfectly mimic the function of the cellular CDK2 (cyclin dependent kinase) [49] . An evolutionary tree alignment for viral B1R protein kinase (Supplemental Figure S3 ) supports the functional overlap and mimicry with the closely related cellular kinases.