DRD4 and lung cancer: Besides nervous system tumors such as gliomas, glioblastoma, and pituitary tumors,[21, 22, 23] DRD4 is also upregulated in breast cancer,[24, 25, 26] non‐small cell lung cancer,[27] prostate cancer,[28, 29, 30] and colorectal cancer (CRC).[31, 32] Moreover, overexpression of DRD4 is associated with tumor progression and prognosis.