We have developed a novel p21(WAF1) promoter activator screening system based on rapid and facile luciferase activity assay of a model cell system (H1299/tsp53-luc cells), a stable luciferase expression cell line established by transfecting H1299/tsp53 cells with a reporter gene construct pWWP-Luc-BSD. This plasmid was constructed by subcloning the 2.4kb p21(WAF1) promoter and a 2.6 kb of luciferase cDNA fragment activated by the p21(WAF1) promoter into a pMAM2-BSD expression vector containing the blasticidin S deaminase gene (BSD). A BSD-resistant clone H1299/tsp53-luc#4, showing the highest response to p53 activation (by temperature shift from 37 degreesC to 32 degreesC) by luciferase production, was used for screening microbial culture broths. Among approximately 1200 screened samples, trichostatin A related compounds and a new compound, lucilactaene, were isolated. This provides an effective and facile screening system for p21(WAF1) promoter activators which should be of considerable value in the rapid identification of new anticancer agents.