Bartolo Colon, a starting pitcher for the playoffs-chasing Oakland Athletics, has been suspended for 50 games after testing positive for synthetic testosterone, Major League Baseball said Wednesday.

The move comes a week after 2012 All-Star Game MVP and San Francisco Giants outfielder Melky Cabrera was given a 50-game suspension for a positive testosterone test. Colon is the fifth MLB player to be suspended this year after testing positive for performance-enhancing drugs, MLB spokesman Michael Teevan said.

"I apologize to the fans, to my teammates and to the Oakland A's," Colon said in a statement released Wednesday by the Major League Baseball Players Association. "I accept responsibility for my actions and I will serve my suspension."

A 50-game suspension is what the MLB gives players for a first positive test of a performance-enhancing substance under its Joint Drug Prevention and Treatment Program. Testosterone is considered such a substance under the program.

"The Oakland Athletics are disappointed to learn of today's suspension of pitcher Bartolo Colon," the Athletics said in a statement Wednesday. "The organization fully supports Major League Baseball's Joint Drug Prevention and Treatment Program and its efforts to eliminate performance-enhancing substances from our game. Per the Basic Agreement, the A's will have no further comment."

Colon, 39, is 10-9 this season, with 24 starts and a 3.43 ERA. He won his last start, an 8-5 decision over the visiting Cleveland Indians on Saturday.

As of Wednesday afternoon, the A's, 66-56, were five games behind Texas in the American League West and a half-game behind Tampa Bay and Baltimore in the chase for two wild-card playoff spots.

With 37 games left on the A's 2012 schedule, the suspension will ensure Colon will miss the rest of the regular season.