The entire open reading frame, encoded by a single exon, was replaced with an EGFPf-2A-FLP-ACN cassette. Farnesylated EGFP (EGFPf) was fused to FLPo (codon optimized FLP recombinase) via foot-and-mouth disease virus 2A peptide (FMDV 2A or F2A) sequence and was ligated to the self-excising loxP-flanked pol-II promoter-neomycin resistance cassette (ACN). Cre-mediated recombination removed the neo cassette.