Phospho-NF-kB p105/p50 (Ser337) is a phosphorylated form of the NF-kB subunits p105 and p50, which are crucial in the regulation of gene expression, particularly in response to various stimuli such as inflammation, immunity, differentiation, cell growth, and tumorigenesis. Phosphorylation at Ser337 is significant for the transcriptional activity of these subunits. It has been shown that phosphorylation at this site can affect the dimerization of p50 and its interaction with DNA. Specifically, phosphorylation by protein kinases like PKAc and Chk1 influences the ability of p50 to form homodimers and bind to DNA, which in turn modulates the transcriptional output of genes under the control of NF-kB. This phosphorylation event is also implicated in the gene-specific regulation of transcription, offering opportunities for selective targeting of NF-kB for therapeutic benefits. Thus, Phospho-NF-kB p105/p50 (Ser337) is a critical regulatory point in the NF-kB signaling pathway, impacting the transcriptional program that governs key physiological processes and disease states.