Chimeric constructs containing a single-chain antibody directed against the human ErbB-2 receptor have been previously demonstrated to redirect T-cell specificity towards mouse epithelial cells transformed to express the human ErbB-2 and human ErbB-2+ MDA-MB453 breast cancer cells (Moritz et al, 1994; Altenschmidt et al, 1997). This evidence concerns the gene ERBB2 and breast cancer.