In primary vs. metastatic carcinomas, CXCL12, CD44v6, CK7, HIF1A and TGFBR2 were differentially expressed at p < 10−6; the level of expression of all the above-mentioned genes from exosomes of metastatic carcinoma were downregulated as compared to tissue samples where CD44v6 was upregulated and the other genes had a downregulated expression. The gene discussed is CXCL12; the disease is metastatic carcinoma.