GSK3B and neoplasm: These results observed in vitro contradict a phase II study of 15 patients with low-grade neuroendocrine tumors treated with LiCl that showed non-positive results in terms of response evaluation criteria in solid tumors and in overall survival, as well as GSK3β phosphorylation [168], suggesting that therapeutic usage of lithium depends on various factors, such as tumor nature and aggressiveness, lithium salts, and doses that allowed GSK3β phosphorylation, among others.