Is there a lacZ reporter in the pLKO.1 vector?
As the vector diagram shows, there is a lacZ alpha reporter and lacZ promoter on the pLKO.1 vector. This is a remnant from the vector creation only. As the reporter is separated from the promoter, it is non-functional. In addition, as the lacZ is not between the LTRs, it will not be integrated into the cells.