Notable genes found to be differentially methylated between tumour subgroups and normal tissue include CTSZ, a lysosomal enzyme which has found to be overexpressed in hepatocellular carcinoma32 and which was hypomethylated in tumours in Cluster A, as well as SPRR3 which encodes the protein Esophagin which has been implicated in tumour cell proliferation and invasion in glioblastoma multiforme33, and has been shown to be upregulated in colorectal cancer34. Here, CTSZ is linked to neoplasm.