Therefore, HIV-1 integration sites that are enriched in long-term in vitro culture support the findings on how HIV-1-infected cells persist by having proviruses integrate in cancer-related genes in a location- and orientation-dependent manner, although the exact HIV-1 integration site may be different from those observed in vivo (i.e., STAT3 identified in vitro [82] is not one of the six enriched genes identified in vivo [81]). This evidence concerns the gene STAT3 and cancer.