CXCR4 is found to be a prognostic marker in many different cancers, including leukemia, breast, lung, prostate, ovarian and CRC, where the stromal cell‐derived factor‐1 (SDF‐1)/CXCR4 axis (also called CXCL12/CXCR4 axis) initiates divergent signaling pathways, including PI3K/AKT, MAPK, and JAK/STAT signals, which can result in a variety of responses such as chemotaxis, cell survival and/or proliferation, increase in intracellular calcium, and gene transcription.601, 602. The gene discussed is PIK3CD; the disease is leukemia.