Celebrity Mary-Kate and Ashley Olsen Show Up for Shopping and More! By Sharon Clott Kanter Sharon Clott Kanter Sharon Clott Kanter is a New York-based writer, editor, and producer who covers fashion, beauty, and pop culture. She was previously the Senior Editor for InStyle and currently teaches fashion journalism at Syracuse University. InStyle's editorial guidelines Published on January 26, 2012 @ 11:50AM Pin Share Tweet Email Photo: Kevin Mazur/Getty Images Mary-Kate and Ashley Olsen partied to support JCPenney and the retailer's grand new plans—like slashing prices by 40% and new designer collaborations—at Pier 57 in New York City. The twins design a juniors line for the store named Olsenboye. Click through the gallery to see Kate Beckinsale, Drew Barrymore, and more stars at last night's hottest parties!