Additionally, hcmv-miR-US4-5p was reported to promoted apoptosis via inhibition of p21-activated kinase 2 expression in cultured cells which may establish a balance between the host cell and virus during natural HCMV infection [27], however, whether or not this HCMV-encoded-miRNA as the regulatory molecules in order to maintain HCMV latent state in vivo and the difference expression pattern between in vivo and in vitro remains to be further verified. This evidence concerns the gene PAK2 and cytomegalovirus infection.