Figure 3. Fibroblast exosomes influence cellular signaling in CRC cells resulting in resistance to chemotherapy and altered proliferation. (A) Western blot demonstrating ERK (left), AKT (middle) and Bad activity (right) in DLD1 cells in the absence and presence of MRC5 exosomes. MRC5 exosomes induced ERK, AKT and Bad (serine 99) phosphorylation but total ERK, AKT and Bad expression was unchanged. HSP90 was used as an equal loading control. (B) Apoptosis of DLD1 cells induced by oxaliplatin in the absence and presence of MRC5 fibroblast exosomes. Fisher’s exact test: *** p<0.001. (C) Proliferation of DLD1 CRC cells in the absence and presence of MRC5 fibroblast exosomes. A significant proliferation defect occurs from day 3 onwards in exosome-exposed CRC cells. Cell counts are relative to day 0, which was given the value 1. Data is presented as mean +/- SEM. Paired t-test: ns – not significant, * p<0.05, ** p<0.01, *** p<0.001.