Western blots of the HTLV-1 Gag proteins from transfected-cell lysates (A) and virus pellets (B). Lanes 1 and 6, wild-type provirus; lanes 2, Pro118-Leu; lanes 3, Pro119-Leu; lanes 4, Pro120-Leu; lanes 5, Tyr121-Asp; lanes 7, wild-type/PR(−); lanes 8, Pro118-Leu/PR(−); lanes 9, Pro119-Leu/PR(−); lanes 10, Pro120-Leu/PR(−); lanes 11, Tyr121-Asp/PR(−). p55Gag, Gag precursor; Tax, transactivator protein; p36, Gag cleavage intermediate.