Considering the low correlation between NDUFS1 protein and mRNA levels in tumor, as well as the fact that the decreased promoter methylation of NDUFS1 was not consistent to the low expression of NDUFS1 mRNA in KIRC (Supplementary Figure S6), we speculated that the expression level of NDUFS1 was probably regulated at the post-transcriptional level. The gene discussed is NDUFS1; the disease is neoplasm.