HERV-K–related genomic and platelet RT-PCR–derived clones encode an apparently full-length pol protein. (A) shows SDS-PAGE of E-PCR products detected by fluorography. Lanes are (from left to right) M, marker; −, reticulocyte lysate, no exogenous DNA added; 1 through 9, individual HERV-K–related clones; 10, MPMV control; 11, HERV-K10. The arrow indicates the full-length protein produced by HERV-K10.