Enterovirus cis-acting replication element is a small RNAhairpin in the coding region of protein 2C as the site in PV1(M) RNA that is used as the primary template for the in vitrouridylylation. The first step in the replication of the plus-stranded poliovirus RNA is the synthesis of a complementary minus strand. This process is initiated by the covalent attachment of Uridine monophosphate (UMP) to the terminal protein VPg, yielding VPgpU and VPgpUpU.