βGBP is a novel physiological negative growth regulator of the cell and a cytostatic factor.It is secreted by cells, and bybinding with high affinity to specific cell surface receptors. In normal cell surface receptors. In normal cells, βGBP physiologically controls transition from G0 to G1 and passage from late S phase to G2 by modulating signalling cascades activated by tyrosine Kinase receptors and by affecting transcription events.As a cytostatic Factor βGBP has a marked growth inhibitory effect on a variety of tumours including leukaemias where growth arrest is followed by the activation of apoptotic pathways and cell death.