The San Francisco 49ers announced they have signed center Marcus Martin to a four-year deal. READ: OTA Highlights and Observations Martin (6-3, 321) was the first of three, third-round draft picks (70th overall) by the 49ers in this year's NFL Draft out of the University of Southern California. He played in a total of 38 games (33 starts) over three seasons with the Trojans. In 2013, Martin started all 13 games at center and helped USC rush for 2,419 yards and 29 touchdowns. He was named a team captain, earned consensus First-Team All-Pac-12 honors and was selected the Trojans Offensive Lineman of the Year last season.