passing value of a textbox from one panel to other

I am a newbie.
asp.net, C#
how to pass a value of a textbox from one panel to other in the same form.
<asp:TextBox ID="txtCtc" runat="server" Width="240px"></asp:TextBox>  in panel 1
 <asp:TextBox ID="textbox1" runat="server" Width="240px" readonly="true"></asp:TextBox> to panel 2
 
 
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