Schreyer et al., Endocrinology 2003
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In human skeletal muscle cells, both IRS-1 and IRS-2 are rapidly phosphorylated on tyrosine in response to insulin, whereas essentially no tyrosine phosphorylation of IRS-4 was observed in response to both insulin and IGF-I Cuevas et al., J Hepatol 2007
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Herein, we report IRS-4 expression in a human hepatoblastoma cell line ( HepG2 ) and IGF-I dependent IRS-4 tyrosine phosphorylation
Madoff et al., Biochem J 1988
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Whereas pp160 remains maximally phosphorylated on tyrosine for up to 60 min in the presence of 100 nM-insulin, IGF-1 at the same concentration induces only a transient response that is maximally 50 % of that observed with insulin