NIK protein, also known as NF-κB-inducing kinase or MAP3K14, is a central component of the non-canonical NF-κB signaling pathway and plays a crucial role in various biological processes, including immunity, development, and disease. NIK is essential for the activation of the non-canonical NF-κB pathway, which is involved in the development of lymph nodes and other secondary immune organs. Recent studies have shown that NIK is also a key regulator of T cell metabolism and antitumor immune responses. It maintains the metabolic fitness of T cells by controlling the cellular redox system, which is crucial for the stability of hexokinase 2 (HK2), a rate-limiting enzyme in the glycolytic pathway. NIK's activity is tightly regulated, and its dysregulation has been implicated in various disorders, including cancer. In a study published in Nature Immunology, researchers found that NIK is critical for T cell activation and metabolic reprogramming, making it a potential target for enhancing antitumor immunity and improving the efficacy of adoptive T cell therapies.