S100A4 and neoplasm: Notably, although CAFs and tumor-associated mesenchymal stem cells (TA-MSCs) are derived from the same cells (primitive mesenchymal stem cells), TA- MSCs have greater self-renewal capability and low expression of markers associated with CAFs such as wave proteins, fibroblast activation protein (FAP) and fibroblast-specific proteins 1 (FSP1, or called S100A4), which warrants further mechanistic studies (45–47).