We first prepared a plasmid encoding CD43, whose intracellular domain was replaced with yellow fluorescent protein (CD43EX‐YFP), and a chimeric receptor bearing an extracellular antigen recognition site (model antigen: a well‐known breast cancer marker, human epidermal growth factor receptor 2 (HER2); single‐chain variable fragment (scFv) against HER2: ML398), the transmembrane domain from CD28, and intracellular cyan fluorescent protein (ML39‐CD28TM‐CFP). This evidence concerns the gene ERBB2 and breast cancer.