Query the radio button itself, not the panel. The radio button does have a tag and other properties. Only use the panel for the click callback.
radioChecked = get(handles.radioButton1, 'Value');
Never use assignin() - it's virtually never needed. I've written hundreds or thousands of programs and have never needed to use it. You don't want to be transferring and collecting all your variables into the base workspace - that is bad practice. There is a reason why there are different workspaces - you want to keep things in scope only where they should be in scope, not visible to the whole computer where some other function, which decided to use the same variable name for a different purpose, suddenly stomps on the variable you had set from a different function.
