The Department of Justice has given the green light to insurance giant Cigna Corp.'s planned $67 billion acquisition of pharmacy benefit manager Express Scripts. The move terminates the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, one of the conditions necessary to close the deal, officials said in an announcement on Monday. The transaction still remains subject to certain state regulatory approvals and filings, including clearances from certain departments of insurance.