To identify novel combinations of small-molecule inhibitors that target DNA replication in cancer cells, we screened a selection of crude extracts of Chinese herbal medicines for their ability to differentially impede cell growth and induce γ-H2AX foci in MCF-7 human breast cancer cells relative to non-cancerous BJ hTERT-immortalized human fibroblasts. The gene discussed is H2AX; the disease is breast carcinoma.