CXCR4 and cancer: Analyses on day 28 revealed amplified interference of CXCR4 downstream signaling by P-BS-CM1 → P-CM2, with pleiotropic effects on blocking pro-metastatic processes: (i) Investigation of tumor desmoplasia revealed that, compared to free BS and P-BS, P-BS-CM1 → P-CM2 resulted in reduced collagen deposition in the tumor matrix as evidenced by the lowest levels of intratumoral α-smooth muscle actin (α-SMA, a cancer-associated fibroblast (CAF) marker), fibronectin (an extracellular matrix component produced by CAFs), collagen hydroxyproline, and fibrosis (Fig. 6b and Supplementary Fig. 12).