Mice that were cured of RIF-1 EGFP tumours by BPD-PDT, mice that had their RIF-1 EGFP tumours surgically removed and untreated control mice were rechallenged by a second injection of 1 million RIF-1 EGFP cells after they had been tumour-free for 60 days. This evidence concerns the gene RIF1 and neoplasm.