Human alphaherpesviruses are common human pathogens associated with a variety of diseases. The striking characteristics of the viruses are to establish a latent infection in neurons after lytic infection at the periphery. The alphaherpesvirus genes have been shown to fall into several major groups (designated alpha, beta, and gamma) whose expression is coodinately regulated and sequentially ordered in a cascade fashion during the lytic cycle of alphaherpesvirus infection. Recently, cellular proteins which interact with alphaherpesvirus regulatory proteins have been identified and the studies have revealed that the regulatory proteins interact with and modulate a plethora of cellular components and functions including transcription, cell cycle, protein degradation pathway, and translation. These findings suggest that they are multifunctional protein and the functions of the regulatory proteins result from the sum of these interactions.