Effect of patient navigation on colorectal cancer screening in a community-based randomized controlled trial of urban African American adults Hisani N. HorneDarcy F. Phelan-EmrickCraig E. PollackDiane Markakis • Jennifer WenzelSaifuddin AhmedMary A. GarzaGary R. Shapiro • Lee R. BoneLawrence B. JohnsonJean G. Ford