ALX 40-4C is a synthetic peptide primarily used in research settings to study its potential as an antiviral and anticancer agent. It specifically inhibits HIV infection by antagonizing the CXCR4 receptor, a key co-receptor essential for viral entry into host cells, thereby disrupting viral replication. In cancer research, ALX 40-4C has been investigated for its role in blocking CXCR4-mediated signaling pathways that promote tumor cell migration, invasion, and metastasis, positioning it as a candidate for therapeutic development. Additionally, its interactions with cellular receptors and signaling pathways continue to be explored for broader biological effects and novel treatments for various diseases. Its applications remain experimental, with ongoing studies to evaluate efficacy and safety prior to clinical use.