The evening and weekend anchors of NPR's flagship newsmagazine program All Things Considered will be undergoing changes in the coming weeks. Show veterans Robert Siegel and Audie Cornish will be joined by ATC's London correspondent Ari Shapiro and national correspondent Kelly McEvers. The new hosts will be replacing Melissa Block, who after 12 years hosting the show, will be exiting in August. Michel Martin will become the new weekend host of ATC, replacing Arun Ruth, who will be exiting Los Angeles and moving back home to Boston. The host changes go into effect in September.