Regorafenib was demonstrated to possibly exhibit antitumor activity on a breast cancer cell line via, at least in part, modulation of the P2X7/HIF-1α/VEGF, P2X7/P38, P2X7/ERK/NF-κB, and P2X7/beclin 1 signaling pathways. The gene discussed is NFKB1; the disease is breast cancer.