The transposon containing an unspecified hybrid actin promoter driving expression of red fluorescent protein (RFP) flanked by piggyBac-specific left and right terminal sequences was co-injected with a piggyBac-containing transgene to mobilize the transposon. The insertion site is located in the third intron of the gene. qRT-PCR, western blot and immunofluorescence analyses indicated nearly undetectable mRNA and protein expression levels in the brainstem of homozygous mice. (J:123680, J:326576)