All of strains were BY474-derivative haploids and grown to exponential phase in liquid YPD at 30°C unless stated otherwise. (A) Schematic representation of pheromone and filamentous growth pathway. For details, see the Introduction. (B) MY13049, 13122, 13144 and 13281 were photographed. (C and D) Indicated strains (MY8092, 12156, 12158, 12886, 12941, 12948, 13122, and 13281) harboring FRE(Ty)-lacZ (MR6857) were used. (E) The budding pattern of fus3Δ kss1Δ (MY13289) was analyzed as described in Fig 2B–2D. (F and G) MY8092, 12156, 12941 and 12948 strains were used. (F) Strains carry FUS1-lacZ (MR0727). (G) Intensities of phosphorylated Fus3p and Kss1p were normalized to total Fus3p and Kss1p and expressed relative to WT. (H) Indicated strains (MY8092, 13049, 13144, 13484, 13523, 13525, 14319, 14320, 14321, 14322, 14323, 14324, 14325, 14326, 14327, 14328, 14329 and 14330) harboring FRE(Ty)-lacZ (MR6857) were used. (I) Indicated strains (MY8092, 12886, 13049, 13144, 13523, 13525, 14319, 14320, 14321, 14322, 14323, 14324, 14325, 14326, 14327, 14328, 14329 and 14330) were used. (C, D, F, and H) Cells were grown to exponential phase in liquid SC containing 2% glucose. The activity of β-galactosidase was determined as described in Materials and Methods and expressed relative to wild type. Data are mean ± standard deviation from three independent experiments. (D and H) WT are identical to (C). (G and I) Active Fus3p and Kss1p were shown by phospho-p42/44 MAPK antibody. Total Fus3p, Kss1p and Kar2p were detected with anti-Fus3p, -Kss1p and -Kar2p respectively. (B and E) Bar, 10 μm.