Identification of CK2 and PKA phosphorylation sites of PEDF by site-directed mutagenesis. (A) rPEDF and rPEDF mutants (indicated) were phosphorylated by CK2 as described in “Materials and methods.” Reaction was arrested by sample buffer and samples were subjected to 10% SDS-PAGE. The gel was stained with Coomassie blue (Coom, bottom panel), dried, and subjected to autoradiography (Auto, top panel). (B) rPEDF and rPEDF mutants (indicated) were phosphorylated by PKA as described in “Materials and methods.” Samples were subjected to 10% SDS-PAGE, stained with Coomassie blue (Coom, bottom panel), dried, and subjected to autoradiography (Auto, top panel). (C) Quantitative analysis of the autoradiogram depicted in panels A-B is presented as a mean ± SD of 6 distinct experiments.