We studied the expression of the PRKCA gene by using the Human Fetal MTC and Human Immune System MTC cDNA panels (Clontech, Palo Alto, California, United States), and found it to be expressed in the relevant immunological tissues, like thymus, lymph node, and pool of blood leukocytes, as well as in a target tissue, the brain (unpublished data). This evidence concerns the gene PRKCA and medullary thyroid gland carcinoma.