She was actually first offered the role in 2011, but she didn't want to leave her two sons, whom she raised without a nanny.
She told CNN, "I couldn't even imagine that was something I could do. Especially with young kids. My kids were early teens at that time."
However, playing Roxie helped Pamela discover talents she didn't realize she had.
She said, "It's incredible because I didn't realize – obviously, your voice, it's a muscle, and so every day my voice is getting stronger and stronger to the point where I'm just looking behind me going, who's singing like that?'"