Question: what hormone is most important in the proliferative phase of the uterine cycle
[{'answer': 'estrogen', 'provenance': [{'wikipedia_id': '88003', 'title': 'Menstrual cycle', 'start_paragraph_id': 5, 'start_character': 46, 'end_paragraph_id': 5, 'end_character': 54, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '88003', 'title': 'Menstrual cycle', 'start_paragraph_id': 82, 'start_character': 0, 'end_paragraph_id': 82, 'end_character': 541, 'bleu_score': 0.852077140730596, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13147405792270922309}, 'section': 'Section::::Cycles and phases.:Uterine cycle.:Proliferative phase.\n'}]}]