Phospho-p70 S6 Kinase (Ser411) Antibody detects endogenous levels of p70 S6 Kinase only when phosphorylated at Serine 411. This gene encodes a member of the RSK (ribosomal S6 kinase) family of serine/threonine kinases. This kinase contains 2 non-identical kinase catalytic domains and phosphorylates several residues of the S6 ribosomal protein.