Neuroendocrine tumors (NETs) are rare, with an incidence of 2 to 5 per 100,000 people. These tumors secrete hormones such as 5-hydroxytryptamine (5-HT) (serotonin), chromogranin A (CgA), neuron-specific enolase (NSE), and synaptophysin. These hormones can cause debilitating symptoms of carcinoid syndrome in patients with neuroendocrine malignancies, such as flushing, diarrhea, heart palpitations, and congestive heart failure. NETs also frequently metastasize to the liver long before they are diagnosed, making curative resection unlikely. Traditional methods of cancer treatment, such as chemotherapy, have not been successful in the treatment of NETs. Therefore, it is imperative that new therapies targeting the signaling pathways involved in NETs are developed.Many of the signaling pathways, which are now known to play an important role in the development and progression of NETs, were initially discovered and studied in other cancers. The phosphatidylinositol 3-kinase (PI3K)-Akt pathway has been well characterized in ovarian cancer, breast cancer, melanoma, and colon cancer. Inhibition of this pathway suppresses the growth of both small cell lung cancers and gastrointestinal carcinoids. Similarly, Notch1 was first studied as an oncogene in pancreatic cancer, colon cancer, non-small cell lung cancer, and various lymphomas. It was then discovered that Notch1 plays the role of tumor suppressor in small cell lung cancer, pancreatic carcinoids, and medullary thyroid cancer. The Ras/Raf/mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway has also been reported to play an oncogenic role in colon cancer, lung cancer, and