... showing the presence of the tetraphosphorylated isoform, revealed a moreextensive post-translational modification of the amni-otic fluid protein. Because the process can be the con-sequence of a ... by the amniotic fluid pro-tease and suggest that not only the degree, but also the position of the phosphate groups influence the process.As for the other IGFBPs, the proteolytic cleavage of IGFBP-1 ... documented.IGFBP-1, the subject of the present study, is predom-inantly expressed in the liver and, in adult mammals, the synthesis of the protein is upregulated in a number of catabolic or stressful...