Source: Mike Wilkening, NBC Sports Pro Football Talk 
After missing Wednesday and Thursday with a knee ailment, Lions wide receiver Calvin Johnson resumed practicing on Friday, Tim Twentyman of DetroitLions.com reported late this morning.
WR Calvin Johnson and DE Ziggy Ansah back at #Lions  practice. Designations out at 4 pm. Bill Bentley and Montell Owens still not practicing.
— Tim Twentyman (@ttwentyman) November 15, 2013