As representatively shown for three selected melanoma cell lines and HaCat as a control, the upregulation of HLA class II mRNA (Figure 3) and surface expression (Figure 2a) by IFN-γ was associated with an increased expression of some HLA class II APM components, e.g., HLA-DO, HLA-DM, CIITA, CLIP and cathepsin S (Figure 3). The gene discussed is CTSS; the disease is melanoma.