The Cowboys tried bulking up their protection for quarterback Drew Bledsoe on Wednesday by signing tackle Marc Colombo, who had started seven games for the Chicago Bears since being a first-round pick in 2002. Colombo played 18 games over the 2002-04 seasons for Chicago. He went to training camp with the Bears, then was cut Sept. 13. The Cowboys, who had a vacant roster spot, have lacked depth at tackle all season, especially since left-side starter Flozell Adams was lost for the season to a knee injury. Sixth-round pick Rob Petitti starts on the right side.