passages.id: split_8_test_244_passage
passages.type: progene_text
passages.text: Microinjection of synthetic SSAP mRNAs encoding either serine or threonine phosphorylation mutants results in the failure to transactivate reporter genes that contain the enhancer element , suggesting that both serine and threonine phosphorylation of SSAP are required for the activation of the late H1 gene .