Protein phosphorylation is a post-translational modification in which a phosphate group is added to a protein molecule, typically by a protein kinase enzyme. This modification plays a crucial role in regulating various cellular processes, including cell signaling, gene expression, cell division, and metabolism. Phosphorylation can alter a protein's conformation, activity, stability, and localization within the cell, thereby influencing its function. Dysregulation of protein phosphorylation has been implicated in numerous diseases, including cancer, neurodegenerative disorders, and metabolic disorders. Studying protein phosphorylation is therefore essential for understanding cellular signaling pathways and developing targeted therapies for disease treatment.