NKX6-2 and renal cell carcinoma: Analogous to previous results revealing an association of methylation in INA, NHLH2, and THBS4 with the metastatic state of tissues [20], we analyzed the relevance of methylation in NKX6-2 to RCC metastasis and whether combined application of CpG-based methylation information for the four genes provides information that improves the detection of metastatic tissues or metastasized primary cancers.