BTLA and nonpapillary renal cell carcinoma: Analysis of methylation revealed that most immunoregulatory genes are highly methylated in different IS of ccRCC, including TNF, CXCL10, IFNG, IL12A, IFNA1, PDCD1, BTLA, KIR2DL1, ITGB2, MICB, HLA-C, HLA-DRA, HLA-DRB1, ARG1, and HMGB1.