A member of the Minnesota Democratic–Farmer–Labor Party (DFL), she represents District 51A, which includes portions of the city of Eagan in Dakota County, which is in the southeastern part of the Twin Cities metropolitan area.

She is also a business woman, working in financial services, real estate sales and insurance.

[1] Masin graduated from Maple Heights High School in Maple Heights, Ohio then went on to Valparaiso University in Valparaiso, Indiana, where she majored in Government and minored in Economics, earning a B.A.

During her first two terms, she was a member of the House Public Safety Policy and Oversight Committee, and also served as vice chair of the Commerce and Labor Subcommittee for the Telecommunications Regulation and Infrastructure Division, and as a member of the Finance subcommittees for the State Government Finance Division, the Transportation and Transit Policy and Oversight Division, and the Transportation Finance and Policy Division.

She has also served on the Burnsville-Eagan-Savage School District's Community Education Advisory Council, the Dakota Council for Health Communities, the Dakota County League of Governments, the Legislative Advisory Committee of the League of Minnesota Cities, the Dakota County Agricultural Society Board and the local League of Women Voters.