Component of the 40S small ribosomal subunit (By similarity). Plays an important role in controlling cell growth and proliferation through the selective translation of particular classes of mRNA (By similarity). Ribosomal protein S6 is the major substrate of protein kinases in eukaryote ribosomes. The phosphorylation is stimulated by growth factors, tumor promoting agents, and mitogens. It is dephosphorylated at growth arrest. Belongs to the eukaryotic ribosomal protein eS6 family.