BRCA1 and cancer: In an attempt to determine whether exosomes shed by cancer cells are more prone than their normal counterpart to internalize into target cells, we isolated exosomes from normal fibroblasts exposed to the serum of healthy individuals (i.e. normal cells) and exosomes from BRCA1-KO fibroblasts after treatment with serum from CRC-LM patients (i.e. transformed cells).