Phosphorylation of HIV-1 matrix protein is necessary for nuclear targeting of viral preintegration complex: A.G. Bukrinskaya1, A. Ghorpade2, A.M. Ragland2, N.K. Heinzinger2, T.E. Smithgall3, R.E. Lewis3, M. Stevenson2, 1D.I. Ivanovsky Institute of Virology, Moscow, Russia; 2Department of Pathology and Microbiology, University of NE Medical Center, Omaha, NE; 3Eppley Institute for Research in Cancer and Allied Diseases, University of NE Medical Center, Omaha, NE