Gas1 (Saccharomyces cerevisiae), Phr1 and Phr2 (C. albicans), Gel1 and Gel2 (A. fumigatus) act actively in the biosynthesis and morphogenesis through the correct incorporation of glucan molecules in the cell wall being also related to the virulence of C. albicans and A. fumigatus in a murine model of infection (Ghannoum et al., 1995; Mouyna et al., 2005). This evidence concerns the gene GAS1 and infection.