CXCR4 and cancer: In our relentless effort to understand the role of chemokine receptor signaling inhibition in cancer therapy18,21–24, here we revealed that neither CXCR7 nor CXCR4-CXCL12 signaling axis is responsible for therapy resistance and tumorigenic potential, rather CXCR4 intracellular protein in the cancer cells plays critical role in positively modulating pro-tumorigenic functions such as therapy resistance in breast and colon cancers.