B. Systematic phospho-Y2H interaction mating approach to identify the active kinase(s) modulating phosphorylation-dependent PPI. One yeast strain (L40matα) co-expressing the interacting bait and prey proteins and was mated against the 266 kinases in the array (L40mata) in a pairwise manner. The growth patterns of the diploid yeast strains that express bait, prey and one kinase from a third plasmid, indicate phospho-modulation of protein interactions. 