To investigate the effect of the p2 peptide on HIV infection, MAGIC-5 cells [1 × 104 CCR5- and CXCR4-expressing HeLa/CD4(+) cells] were infected with HIV-1JRFL in the presence or absence of the Tat-p2 peptide or Tat-scrambled peptide (GRKKRRQRRRARVLIAVSNMQTTAMATE). This evidence concerns the gene CXCR4 and HIV infectious disease.