Human CXCL12 alpha (stromal cell-derived factor 1 alpha, SDF-1alpha) is a 68 residue CXC chemokine critical for cell migration and tissue development. Secreted by stromal cells, endothelial cells, and others, it primarily binds to the CXCR4 receptor to regulate hematopoiesis, immune cell trafficking, and organogenesis. It also binds the ACKR3 and ACKR5 scavenger receptors. CXCL12 attracts lymphocytes, monocytes, and stem cells, playing a key role in immune surveillance, wound healing, and embryonic development. Dysregulation is linked to cancer metastasis, HIV infection (as CXCR4 is an HIV co-receptor), and inflammatory diseases. Seven isoforms (alpha, beta, gamma, delta, etc.) arise due to alternative pre-mRNA splicing and vary mainly in tissue expression and the length and composition of a C-terminal sequence extension.
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