TAT-YFP-R18 dimer is able to transduce into human leukemia KG-1a cells expressing FGFR1OP2-FGFR1 fusion and effectively induces apoptosis. (A) Schematic diagram of the structure of TAT-YFP-R18 dimer and -R18 mutant. Amino acid sequence of the TAT protein transduction domain is indicated. (B) Induced expression of recombinant TAT-YFP-R18 proteins in bacteria by IPTG. The fusion proteins were purified, and the purification efficiency was determined by Coomassie blue staining. (C) TAT-YFP-R18 dimer transduces into and induces significant apoptosis in KG-1a cells but not in control HL-60 and Jurkat T cells. The cells were incubated with TAT-YFP-R18 proteins for 6 hours, followed by staining with antiannexin V reagent and analysis by FACS for the apoptotic population that is characterized as the fraction of annexin V/YFP double-positive cells in total YFP-positive cells (%). Indicated P values were determined by the Student t test. Transduced TAT-YFP-R18 proteins were detected by Western blotting.