James Collins scored and was sent off as Luton drew 1-1 at Cambridge in League Two.Collins put the league leaders ahead 12 minutes before half time, turning the ball home after David Forde had parried Danny Hylton's shot from the edge of the box.They had come within inches of taking the lead moments earlier, when Luke Gambin carried the ball down the left and pulled it back to Olly Lee, whose shot went wide via the outside of the post.Luton's task was made more difficult 14 minutes from time when Collins was shown a second yellow card in a matter of minutes, first for a handball and then for dissent at the award of a Cambridge corner.Cambridge pressed with their numerical advantage and made it count seven minutes from the end when Brad Halliday provided a perfect cross for substitute Jabo Ibehre, who thumped a header past Marek Stech.The U's could have won it soon after but Ibrehre and George Maris saw shots blocked in a scramble close to goal.