ELAVL4 and small cell lung carcinoma: Since these are both immunologically privileged sites–because of vascular barriers and low HLA expression [32,33]–the HuD in SCLC is effectively tumour-specific, analogous to the well-known cancer-germline antigen NY-ESO-1 [34], which is only normally detected in pre-meiotic spermatogonia and spermatocytes [35] (again with low HLA expression).