We screened 23 natural compounds for their cytotoxicity in human normal lung fibroblasts (TIG-3) and three cancer cell types, osteosarcoma (U2OS; wild type p53), breast adenocarcinoma (MCF-7; wild type but functionally inactive p53) and HT1080 fibrosarcoma (mutant p53). The gene discussed is TP53; the disease is cancer.