Using HIV-1-chimeric RNA junction analysis, we identified cells which harbor inducible HIV-1 integrated into cancer-related genes found in clonally expanded cells in vivo, such as BACH2 and NFATC3. Thus, both intact and defective HIV-1can be integrated into cancer-related genes, and both intact and defective HIV-1 proviruses can undergo clonal expansion. This evidence concerns the gene BACH2 and cancer.