By crossing the Flp-driven KPF with the ExoBow allele, termed KPF-CD63-mCherry, we achieved Flp-mediated expression of CD63-mCherry specifically in cancer cells (Pdx1-Flp; R26CD63-XFP/+; FSF-KrasG12D/+; Trp53Frt/+; Fig. 1h,i). The gene discussed is PDX1; the disease is cancer.