The targeting vector contains a CMV enhancer/chicken beta-actin core promoter (CAGGS), a loxP-STOP(6xSV40 polyA)-loxP cassette (LSL), an enhanced Acidaminococcus cas12a variant, including several substitutions (E174R/N282A/S542R/K548R; enAsCas12a), a nucleoplasmin nuclear localization signal (NLS), a 3xHA epitope sequence, an SV40 NLS and a rabbit beta-globin polyadenylation signal (RBG pA). Cre-mediated recombination removed the STOP cassette. (J:101977)