Howard (back) will begin a rehab assignment at Low-A Bradenton on Friday, Alex Stumpf of DKPittsburghSports.com reports.
Howard was shut down late in spring training due to back spasms, but it's encouraging that he's now been cleared to appear in minor-league games. It's not yet clear when the southpaw will be able to make his season debut with the Pirates, but he appears to be trending toward a return.