p70 S6 and p90 Rsk kinases. Sequence corresponds to amino acids 231-239 of human 40S ribosomal protein S6; also reactive with additional species, including cow. in addition to phosphorylation by p70 S6 and Rsk kinases, also represents substrate for protein kinase C; specificity can be improved by use of appropriate PKC (sc-3007) and PKA (sc-3010).