UpdatePanel and showing/hiding an ASP.NET Panel

I tried this using CheckBox control for convenience and it works fine. See the sample below:

[ASPX]

<atlas:ScriptManager runat="server" ID="ScriptManager1" EnablePartialRendering="true" /
<atlas:UpdatePanel runat="server" ID="UpdatePanel1">
<ContentTemplate>
<asp:Panel ID="Panel1" runat="server" Height="50px" Width="125px">
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label><br />
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox><br />
<asp:Button ID="Button1" runat="server" Text="Button" /></asp:Panel>
<br />
<asp:CheckBox ID="CheckBox1" runat="server" AutoPostBack="True" Checked="True" OnCheckedChanged="CheckBox1_CheckedChanged"
Text="Show Panel" />
</ContentTemplate>
</atlas:UpdatePanel
[C#]

protected void CheckBox1_CheckedChanged(object sender, EventArgs e)
{
Panel1.Visible = ((CheckBox)sender).Checked;
}