Figure 1.

Summary of presumptive changes in carcinoma-associated fibroblast (CAF) populations, intratumoral heterogeneity, numbers of cancer cells, and percentages of survivor cancer stem cells (CSCs) during therapy and recurrence. In the course of chemotherapy, the majority of cancer cells (blue) are eliminated (grey). In parallel, the percentage of CSCs (red) may increase in minimal residual disease (MRD) compared to the gross tumor mass. During recurrence, daughter cells of the resistant CSCs can repopulate (brown) the tumor. The original CAF population (green) is partially eliminated (grey) by the therapy. Resistant (yellow) and newly formed CAFs may have dedifferentiated from normal fibroblasts (NFs) and from bone-marrow-derived mesenchymal stem cells (BM-MSCs) (purple).