Big business rallied behind the gay marriage cause on Thursday as the U.S. Supreme Court scheduled oral arguments for April 28 on the contentious social issue that promises to yield one of the justices' most important rulings of 2015. A total of 379 businesses and groups representing employers across various sectors, including Google Inc , American Airlines Group Inc , Goldman Sachs Group Inc and Johnson & Johnson , have signed on to a friend-of-the-court brief in support of gay marriage due to be filed later on Thursday.