Temporal regulation, of genes

The expression of FGFs at both the RNA and protein level is generally very low in normal adult tissues peaks of FGF expression often occur in brief phases of embryogenesis. In situ hybridization studies have provided evidence for tissue-specific patterns of FGF mRNA expression in early stages of embryonic development (see Section 4.5). Such spatial and temporal regulation of gene expression correlates well with some of the documented effects of these factors, such as induction of mesoderm (by FGF-2, -3, -4, and other FGFs reviewed by Slack, 1994), or induction of specific primordia such as the limbs (by FGF-2 and -4 reviewed by Niswander et al., 1994 Olwin et al., 1994), the eye (by FGF-1 and -2 reviewed by McAvoy et al., 1991), and the inner ear (by FGF-3 Represa et al., 1991 Mansour, 1994). 

---