<asp:UpdateProgress ID="ProgAjax" runat="server">
        <ProgressTemplate>
            <div align="center">
                <img src="/images/loading.gif" />
            </div>
        </ProgressTemplate>
    </asp:UpdateProgress>

            <asp:UpdatePanel ID="UpdAjax" runat="server" UpdateMode="Conditional" >
        <ContentTemplate>
   
            <asp:Panel ID="PnlArticoloLoading" runat="server" Visible="false">
               'QUI C'è L'ARTICOLO
</asp:Panel>

        </ContentTemplate>
                                <Triggers>
                                    <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" />
                                </Triggers>
                            </asp:UpdatePanel>