STUCK ON YOU: Starlets including Lou Lesage, Aïssa Maïga, Chan Ren and Camille Rowe-Pourcheresse turned out at Chloé on Monday. Marie-Ange Casta said she was following in her big sister Laetitia’s footsteps in more ways than one. “I have just signed with a cosmetics brand, but I can’t tell you which yet,” the model-turned-actress teased. Her first film, “Blind Valley,” opened on Sept. 21 in France, and a second, “Des vents contraires,” will hit screens in December. Marina Vacth was tight-lipped about her next film project, but let slip that her role involved learning German. “It’s scary but also very exciting,” she said. Alexa Chung reckoned she was ripe for a break after launching her second collection for Madewell last month. The London “It” girl was sporting nails encrusted with green rhinestones. “A Japanese girl I know in New York did it, called Nomi, and it was to match with a Mary Katrantzou dress, but now it might look a bit silly out of context. But I can’t take it off. It’s like gel or something — stuck,” she sighed.