The loss of HLA class I expression and therefore subsequent CD8+ T-cell responses in a patient with pancreatic cancer has been observed to be compensated with HLA class II-restricted CD4+ T-cells (with cytokine production and cytolytic activity) (18) arguing that a molecular and immuno-histological examination of cancer lesions should include the MHC class I as well as the MHC class II antigen processing and presentation pathways that can be subject to therapeutic modulations, e.g. using HDAC inhibitors. Here, CD4 is linked to cancer.