Despite T22‐GFP‐H6‐FdU achieved selective depletion of CXCR4+ target cells in tumor tissue observed 48 h after its administration, we found this effect to be transient, since 72 h post‐injection CXCR4+ cancer cell fraction in tumor tissue grew back, nevertheless, to reach a level lower than that basal before therapy (Fig 4A and B). This evidence concerns the gene CXCR4 and cancer.