In addition to the high expression levels found in tumor cells during pathology [42,44], low but specific APLNR immunoreactivity can also be detected in certain discrete brain regions under physiological conditions, which include pyramidal neurons in the striatum and the cortex, the hypothalamic paraventricular and supraoptic nuclei, the pituitary, the pineal gland, and Purkinje cells in the cerebellum [22,24]. The gene discussed is APLNR; the disease is neoplasm.