Proxy server and caching

[John]

We want to prevent the caching in our project, so we have the following
line of code in the page load function

Response.AppendHeader("Cache-Control", "no-store");

But when we are using proxy server and IE, the page is cached to the
local machine.

But the page is not cached with firefox and proxy server.

Any suggestions on how to prevent caching when using proxy server and
IE.