https://www.reuters.com/article/us-facebook-cambridge-analytica-ireland/irish-regulator-following-up-with-facebook-on-third-party-data-use-idUSKBN1GW1FO >Ireland's Data Protection Commissioner, the lead regulator for Facebook in Europe, is "following up" with the U.S. internet giant to ensure its oversight of app developers using its data is effective, it said on Tuesday.