CD44 and breast cancer: In prostate adenocarcinoma, exosomes separated from the CSC and bulk tumor cell fractions showed clearly different effects on CAF precursors, which is less studied in breast cancer.83 Some breast cancer studies used purified exosomes from MDA-MB231 cultures with predominant CD44+/CD24–/low population.84 However, merely being CD44+/CD24–/low does not meet all criteria of CSCs, and it may indicate only some degree of stem-like properties.