PF-670462 is a potent and selective inhibitor of casein kinase 1 delta and epsilon (CK1δ/ε), enzymes involved in the regulation of circadian rhythms, cell cycle progression, and Wnt signaling pathways. It is primarily used in research settings to study the role of CK1 isoforms in biological processes, particularly in circadian clock modulation. By inhibiting CK1δ/ε, PF-670462 alters the phosphorylation state of core clock proteins such as PERIOD (PER), leading to changes in circadian period length in cellular and animal models. This makes it a valuable tool for investigating sleep disorders, mood regulation, and metabolic conditions linked to circadian misalignment. Additionally, due to the involvement of CK1 in neurodegenerative diseases and cancer, PF-670462 has been employed to explore therapeutic strategies targeting CK1-dependent pathways, especially in models of Alzheimer’s disease and certain cancers where Wnt signaling is dysregulated. Its high selectivity and blood-brain barrier permeability enhance its utility in central nervous system-related studies.