Fig. 1.

Regulation of Muc1/Flo11 protein. External signals such as nitrogen starvation activate Ras2, which in turn triggers both MAP kinase and Ras/PKA pathways through a cascade involving Cdc24/Cdc42 and Cyr1, respectively⁸. Several factors from both pathways have been shown to control Phd1 expression including Ste12 and Tec1 of the MAP kinase pathway and Mga1, Sok2, and Flo8 from the Ras/PKA pathway and Phd1 itself¹¹. In addition, Cdk8 which is expressed in normally growing cells has been shown to cause Phd1 and Ste12 protein destabilization¹¹. Ultimately, several filamentous response genes (FRG) including Flo11 are regulated by Phd1, Flo8, Ste12, Tec1, Mga1, and Sok2 and direct the phenotype. Arrows indicate upregulation while lines with bars indicate inhibition^{5, 11}