pFRT/lacZeo and pFRT/lacZeo2 were constructed for establishing Flp-In™ Cell Lines that contain a single FRT site. Each vector includes a:

• FRT site for subsequent targeted integration of a Flp-In™ expression vector
Z-Zeocin™ fusion for selection of stable integrants with Zeocin™

These vectors differ in the SV40 promoter that drives expression of the lacZ-Zeocin™ fusion. pFRT/lacZeo2 contains a truncated version of the SV40 promoter. Use of this vector facilitates the isolation of clones that have integrated the vector near enhancer elements in the genome. Selection of stable clones using pFRT/lacZeo2 may allow easier isolation of clones that express a gene of interest at higher levels.