WEE1 and neoplasm: Protein kinases represent an important group of enzymes crucially involved in controlling survival and tumor progression signals and their inhibition is conventionally obtained by two main classes of compounds: monoclonal antibodies, acting mainly by competition with natural ligands on cell surface tyrosine kinase (TK) receptors, and small molecule inhibitors of natural or synthetic origin, acting also on intracellular enzymes/receptors.