Bello (forearm) threw a bullpen session Sunday with no apparent issues, Pete Abraham of The Boston Globe reports.
Bello was briefly shut down from throwing after he experienced some soreness in his forearm during mid-February, but he's now back on the mound after playing catch over the past week. The Red Sox are likely to remain cautious with the 23-year-old righty this early in camp, but at this point it appears he's avoided any serious issues and should continue ramping up his throwing program.