Question: which second messenger molecule acts on the endoplasmic reticulum to release calcium ions
[{'answer': 'Calcium ions'}, {'provenance': [{'wikipedia_id': '2219538', 'title': 'Calcium signaling', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 365, 'bleu_score': 0.950272555443264, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7735842371118304067}, 'section': 'Section::::Abstract.'}]}]