Cytokinins and cytokinin nucleosides are purine derivatives with potential anticancer activity both in vitro and in vivo. N(6)-furfuryladenosine (kinetin riboside, KR) displays antiproliferative and apoptogenic activity against various human cancer cell lines and has recently been shown to suppress tumor growth in murine xenograft models of human leukemia and melanoma. In this study, we demonstrate that KR is able to inhibit the proliferation in HCT-15 human colon cancer cells in a dose-dependent manner with a concentration of 2.5 μM, which causes 50% inhibition of cell viability. The cell cycle analysis by flow cytometry showed that KR arrested cell cycle progression in the S Phase by blocking through G(2)/M and G(0)/G(1) phase in HCT-15 colon cells. Moreover, suppression of clonogenic activity occurs after exposure to KR at a concentration of 2.5 μM for HCT-15.