NEW YORK (AP) - Department stores that have watched some of their customers flock to second-hand stores are trying to bring them back by partnering with online resale sites.

Last week, J.C. Penney and Macy's announced a pilot program to set aside sections inside a few dozen of their stores for used merchandise sold by ThredUP.

In April, Neiman Marcus bought a minority stake in Fashionphile, an online seller of pre-owned designer accessories. And this fall, it will launch shops inside some of its own stores where customers can sell used designer items to Fashionphile.

The moves mark the most dramatic evidence of how resale is becoming so mainstream that traditional sellers can't ignore it. Analysts see the strategy as a way to drive customers into stores, but it could also undermine business.