HIV-1 matrix protein (MA) is the small multifunctional protein located on N terminus of Gag protein p55. MA posseses three transport signals: membranotropic, nucleophilic and the signal of nuclear export and functions in the cell as shuttle protein. MA is cleaved from Gag precursor by viral protease early in infection and is transported into the nuclei where it associates with viral RNA (vRNA). The complex MA-vRNA is transported to plasma membrane – the place of HIV assembly - usingMA membranotropic signal and phosphorilation. Mutant MA (M4) prepared by Dr. Dupont (USA, Worchester, Medical School) used in association with vRNA lost membranotropic signal and can not move to the plasma membrane. It was located in the nuclei and cytoskeleton. It could be suggested thatmutant MA ”get stuck” during cellular transport. That localization unusual for wild HIV-1 could suggest that wild MA complex with vRNAdelivers vRNA from the nucleus to the plasma membrane through cytoskeleton.