Upon phosphorylation by activated ERKs, ribosomal S6 kinases (RSKs) autophosphorylate on conserved serine residue in the linker region (S380 in RPS6KA1) and a conserved threonine residue at the C-terminal ERK-docking domain (T732 in RPS6KA1) (Dalby et al. 1998, Roux et al. 2003). Autophosphorylation at the ERK-docking domain regulates binding to ERK and duration of RSK activity (Roux et al. 2003).