The nptII gene encodes a selectable marker enzyme, neomycin phosphotransferase II (NPTII), which was used to identify cotton cells containing the Cry1Ac protein. The npt II gene is driven by a cauliflower mosaic virus 35S promoter and followed by a nopaline synthase (nos) 3’ region that directs polyadenylation of the mRNA. The NPT II protein served no other purpose and has no pesticidal properties.