TXN and cancer: In our experiments, B5 induced time-dependent ROS accumulation (Fig. 4A) suppression in TrxR activity and increase in the oxidized Trx form (Fig. 5A and 5D) in cancer cells; furthermore, the ROS scavenger NAC reduced B5-elicited apoptosis (Fig. 4B), suggesting that B5-dependent disruption of the Trx system and excessive ROS accumulation underlie the proapoptotic activity of B5.