S100B and breast cancer: The S100 protein family has been reported to contribute to multiple biological processes, such as growth, cell motility, signal transduction, transcription, cell survival and apoptosis, which are related to normal development and tumorigenesis.4 Accumulating evidence has indicated that the dysregulation of S100 family members correlates with tumor progression in various types of cancers, including breast cancer, liver cancer and colorectal cancer.5, 6, 7, 8 Specifically, S100A2,9 S100A410 and S100A611 are associated with tumor differentiation and promoted tumor growth.