**5.5.3 FGF activation**

FGF1 and FGF2 are the two earliest characterized members of the FGF family of growth factors. FGF is an angiogenic factor that is frequently overexpressed in breast and prostate cancers. Rac1 and Cdc42 have been reported to increase FGF1 expression by stimulating the FGF1 gene promoter region (Chotani, Touhalisky et al. 2000). One study demonstrated that Rac1 activity is required for FGF2-induced activation of Ras/MAPK signaling in human breast cell line MCF7 (Liu, Chevet et al. 1999). In addition, medium collected from RhoC stably transfected HME and SUM149 cells present higher level of FGF2, in comparison to those collected from control transfected HME cells (van Golen, Wu et al. 2000). However, how Rho proteins regulate FGF expression remains unclear.

Fig. 4. Rho family GTPases are involved in different stages of breast cancer progression: dedifferentiation and upregulation of uncontrolled proliferation, angiogenesis, invasion and metastasis.
