passages.id: split_1_test_2621_passage
passages.type: progene_text
passages.text: Further analyses using various probes with or without mutated STAT - binding sequences showed that , although either of the two tandem STAT - binding sequences binds STAT4 weakly , the presence of both is required for significant binding of activated STAT4 and for formation of the STAT4 - DNA - binding complex with lower electrophoretic mobility .