Cloning systems are provided for constructing expression vectors. In one aspect of the invention, a kit is provided for constructing one or more recombinant expression vectors. The kit comprises: a linear driver DNA comprising a promoter sequence, a donor recombination site, and at least one selectable marker, the linear driver DNA being capable of being ligated with one or more linear donor DNA comprising a donor DNA sequence to form one or more circular donor DNA; and a circular acceptor vector comprising an origin of replication and an acceptor recombination site capable of recombining with the circular donor DNA to form the recombinant expression vector for expressing the donor DNA sequence.