Indirubin is the active ingredient 0 1' a traditional Chinese herbal medicine, Danggui Longhui Wan, used for the t reatment of chronic myelocytic leu kelma The author reports that novel indirubin derivative, 5'-nitro-indirubinox ime (5'-NIO) , has potent a nti -proliferative activity on human o1'al cancer cells , Treatment of KB cells with 5’ NIO s howed a s t rong cell growth inhibit ion during indicated time point , A typical apoptosis pattern was obtained with DNA fragmenta tion and i mmunofl uorescence analysis of annelxn-v-f!ous Western blot data revealed that p53 and p21CIP1/Waf- l level increased strongJy upon 5'-NIO treatment , The a uthor next tested whether 5'-NIO could activate apoptos is related proteins s uch as caspase-3/-7/-9, [n cells exposed to 5‘-NIO, activation of caspase-3 and -7 was observed, Interesti ngly‘ caspase-9 and cytochrome c cou ld s li ghtly activate in response to 5’-NIO. These results indicate that 5’-NIO strongly induces oral cancer cells apoptosis via a Mi tochondria-mediated cas pase cascade pathway, These observations together s uggest that 5’ NTO may have a possible therapeutic potentia[ to oral cancer