MATLAB: How can i use a global var with call_back functions

global vargui

The problem is: how can i declare a global var, so i can use it on all functions of my guidata?
for example:
function pushbutton5_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton5 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
---->  cpselect(E,D);
guidata(hObject, handles);
% --- Executes on button press in Inserir.
function pushbutton4_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton4 (see GCBO)
% Invoca duas fotos
echo ImRectOpen off;
----->  global E D;
[E,D]=ImRectOpen();
imshow(E,'Parent',handles.axes3);
imshow(D,'Parent',handles.axes4);
set(handles.pushbutton1,'enable','on');
set(handles.pushbutton5,'enable','on');
guidata(hObject, handles);
First, i've ran the pushbutton_callback4 and then pushbutton_callback5. On pushbutton_callback5 global variables (E and D) that were declared on pushbutton_callback4, cant be found.
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