Which statement correctly distinguishes the roles of protein kinases and protein phosphatases in signal transduction pathways? which statement correctly distinguishes the roles of protein kinases and protein phosphatases in signal transduction pathways? protein kinases activate enzymes by phosphorylating or adding phosphate groups to them. protein phosphatases dephosphorylate or remove phosphate groups from enzymes, including protein kinases. protein kinases are more critical than protein phosphatases to signal transduction enzymes. protein kinases are involved in signal transduction in unicellular eukaryotes such as yeast. protein phosphatases are involved in signal transduction in multicellular eukaryotes.