Show a UserForm that matches the contents of a cell?

Show a UserForm that matches the contents of a cell?

On my spreadsheet, cell E8 will contain the name of a UserForm. For this
example "mainMenu".
On my UserForm "newClient", when the button "btnAddClient" is clicked, I'd
like to unload the "newClient" form and show whichever form matches the
name that is shown in cell E8.
I've tried the following different code but none work. How can this be done?
ActiveSheet.Range("E8").Text.Show
ActiveSheet.Range("E8").Value.Show
ActiveSheet.Range("E8").Show