APAF1 and renal cell carcinoma: The aim of this study was to further investigate the occurrence and relevance of promoter methylation of the p53 target genes death-associated protein kinase-1 (DAPK-1) and apoptotic protease activating factor-1 (APAF-1) in relation to different stages of tumour progression in transitional cell carcinoma (TCC) and RCC.