T22-PE24-H6 specifically delivers a de-immunized 24 kDa catalytic domain of Pseudomonas aeruginosa (PE) exotoxin A to the chemokine receptor CXCR4 overexpressing (CXCR4+) cancer cells by interacting with its T22 ligand 11,16. The gene discussed is CXCR4; the disease is cancer.