[Role of protein phosphorylation in the development of tumors]

Phosphorylation is one of the most important ways of posttranslational modification of proteins that enables regulation of many cell physiological processes (transport, proliferation, differentiation). This reversible and very fast process is involved in all phases of cell division: in transition from G1 to S phase, progression of cells during S phase and entry into M phase. The physiological function of oncoproteins and tumor suppressor proteins that are involved in gene expression and replication are also regulated by phosphorylation. Many growth factors and their receptors are encoded by oncogenes which are mutated or overexpressed in a variety of human tumors. Mutation or overexpression of these oncogenes leads to uncontrollable cell division and transformation of normal cells to malignant. Cancer can be considered as a disease of the signalling pathways.