‘Mamma Mia!’ on stage at McKeesport April 2, 2022 Mon Valley Independent Latest News Mackenzie McDonald gets her make-up done by fellow cast member Ashley Slagle before McKeesport Area High School’s production of “Mamma Mia!” Friday night. Two more shows will be presented at 2 p.m. and 7:30 p.m. today. FacebookTweet FacebookTweet