passages.id: split_1_test_199_passage
passages.type: progene_text
passages.text: In vitro precipitation with a glutathione-S-transferase - fusion protein containing the C - terminal transactivation domain of STAT5a showed GH - regulated association of ERK1 / 2 with the fusion protein , while this was not seen when serine 780 in STAT5a was changed to alanine .