A second-generation E2F1 pathway activator with potential antineoplastic activity. ARQ 171 induces the expression of E2F transcription factor 1, thereby activating the E2F1-mediated checkpoint process. E2F1, down-regulated in cancer cells, regulates expression of genes involved in the cell cycle progression from G1 into S phase. The G1/S checkpoint process selectively induces cell cycle arrest in cancer cells with irreparable DNA damages and triggers subsequent apoptosis, while allowing cell division to proceed in cells without or with minor reparable DNA damage. As a result, this agent exerts anti-tumor activity through checkpoint activation independent of p53 mediated tumor suppression. [ ]