HLA-C and squamous cell carcinoma: DNA methylation is known to be involved in the regulation of CIITA and MHC gene expression in several tumour cell types, including trophoblast-derived cells, a subset of lymphoma cells, and squamous cell carcinoma (Morris et al, 2000; Nie et al, 2001; Murphy et al, 2002; Moreau et al, 2003).