Directcast in C#

[Beast777]

When I used VB I would use directcast to change my Main menu items visibility like this:

DirectCast(Me.MdiParent, frmMain).MenuItem13.Visible = True
            DirectCast(Me.MdiParent, frmMain).MenuItem4.Visible = True
            DirectCast(Me.MdiParent, frmMain).MenuItem14.Visible = True

How do I accomplish the same thing in C#?