FLI1 and neoplasm: Clones that expressed both mutant KRAB/FLI-1 and EWS/FLI-1 displayed a similar tumour growth rate in nude mice to that of the parental EWS/FLI-1-expressing cells; however, clones that expressed KRAB/FLI-1 showed significantly reduced tumour size (Figure 6A and 6B).