Lai et al. unmasked that miR-7 was downregulated in doxorubicin-resistant small cell lung cancer cells, and miR-7 enhancement repressed doxorubicin-induced homologous recombination repair through inhibiting Rad51 and BRCA1 expression, which elevated the doxorubicin sensitivity of doxorubicin-resistant small cell lung cancer cells [34]. This evidence concerns the gene RAD51 and small cell lung carcinoma.