Photographs of simultaneous staining of 30 week old breast tumors arising in HER-2/neu transgenic mice illustrating that over expression of HER-2/neu correlates down regulation of h tid. ErbB-2 was detected using a polyclonal chicken anti rat ErbB-2 and a FITC labelled secondary antibody. Tid was detected using the rabbit polyclonal anti hTid antibody [6, 7, 13] and a Texas Red labelled secondary antibody. The tumor cells over expressing ErbB-2 (A, arrowhead) are characterized by low tid expression (B, arrowhead; cf. Figure 3). In C an overlay of the photographs shown in A and B is presented.