CSK (C-Src Tyrosine Kinase) is a vital regulatory enzyme that controls the activity of Src family tyrosine kinases by phosphorylating and inhibiting them. These kinases play crucial roles in cell growth, differentiation, and survival signalling pathways. Dysregulation of CSK can result in abnormal cell signalling, contributing to cancer and other diseases. Studying CSK’s regulatory functions helps us understand cell signalling control and offers potential targets for therapy in diseases involving tyrosine kinase imbalances.