Standout WR Boldin to have precautionary MRI on troublesome right hamstring

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FLAGSTAFF, Ariz. (AP) -- Arizona Cardinals wide receiver Anquan Boldin will undergo a precautionary MRI today on his sore right hamstring.

Meanwhile, the team is awaiting results of tests conducted on the injured left knee of starting center Al Johnson.

Cardinals officials say the injury either will be treated through rehabilitation or will have to be repaired with arthroscopic surgery.

Johnson missed two games with a knee injury last season.

Arizona reserve offensive lineman Scott Peters was taken off the field in a cart after injuring a knee during yesterday's practice.

The extent of the injury isn't known yet.

In other camp news, the Cardinals signed free-agent offensive tackle Kelly Butler and released tackle Thaddeus Coleman.