NEW YORK — Major League Baseball suspended one of the Cubs’ minor league pitchers on Tuesday, and it comes down to the use of a banned substance.

Dalbert Mosquea, who is pitching for the Cubs’ rookie team in the Dominican Summer League, was given a 56-game suspension without pay after testing positive for Stanozolol. This was announced just ahead of the big league club’s start of their City Series with the White Sox at Wrigley Field.

Use of that performance-enhancing substance is a violation of MLB’s Minor League Drug Prevention and Treatment Program.

The 18-year-old pitcher was signed by the club as a free agent on June 29, first assigned to the DSL Cubs Red team before joining their DSL Blue team. In nine games with that squad, Mosquea had a 3.14 ERA in 14 1/3 innings with 23 strikeouts compared to three walks with a WHIP of 1.05.