The highest expressed GPCRs in PDAC tumors (as an example, this finding is generalizable to other tumor types) are generally overexpressed compared to normal tissue and include orphan receptors (e.g., GPRC5A and ADGRF4/GPR115) and GPCRs with known agonists (e.g., GPR68) (Fig 2A and 2C). The gene discussed is ADGRF4; the disease is neoplasm.