Do you mean this? Which site gets phosphorylated in insulin-resistant HepG2 cells p-IRS1 serine 307 or p-IRS1 serine 312 and which counter tyrosine should I check too?
please see the following articles: Rajan MR, Fagerholm S, Jönsson C, Kjølhede P, Turkina MV, Strålfors P. Phosphorylation of IRS1 at serine 307 in response to insulin in human adipocytes is not likely to be catalyzed by p70 ribosomal S6 kinase. PLoS One. 2013;8(4):e59725. doi: 10.1371/journal.pone.0059725. Epub 2013 Apr 2. PMID: 23565163; PMCID: PMC3614923. and, Danielsson A, Nystrom FH, Strålfors P. Phosphorylation of IRS1 at serine 307 and serine 312 in response to insulin in human adipocytes. Biochem Biophys Res Commun. 2006 Apr 21;342(4):1183-7. doi: 10.1016/j.bbrc.2006.02.075. Epub 2006 Feb 23. PMID: 16516141.