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.
Calvin Johnson Is Back At Practice by Sports Talk Florida
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