Question: what is the primary function of the endoplasmic reticulum
[{'answer': 'transport of synthesized proteins', 'provenance': [{'wikipedia_id': '9775', 'title': 'Endoplasmic reticulum', 'start_paragraph_id': 21, 'start_character': 133, 'end_paragraph_id': 21, 'end_character': 166, 'bleu_score': 1.0, 'section': 'Section::::Functions.\n'}]}, {'provenance': [{'wikipedia_id': '9775', 'title': 'Endoplasmic reticulum', 'start_paragraph_id': 21, 'start_character': 0, 'end_paragraph_id': 21, 'end_character': 1039, 'bleu_score': 0.9700126434602441, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6186051870163808157}, 'section': 'Section::::Functions.\n'}]}]