Compositions, methods, uses and assemblages for the preferential induction of cell division cycle arrest and/or apoptosis, in a first population of cells compared to a second population of cells employ either: (i) an opioid or opioid-like agent and an NF-.kappa.B activating agent, which agents are other than the opioid-like agent trans-U50488 in combination with an NF-.kappa.B activating agent selected from etoposide and nocodazole; (ii) a ligand for a sigma receptor, or (iii) an opioid or opioid-like agent wherein the cells of the first population are other than tumor cells.