Mutation of a PKA consensus phosphorylation motif in Kss1 does not affect either its positive or its negative functions in invasive growth. Strains JCY110 (kss1Δ) and JCY117 (kss1Δ ste7Δ) were transformed with an empty vector (vec; YCplac33) or with plasmids encoding Kss1 (wt; YCpU-KSS1), Kss1(K42R Q45P) [KR; YCpU-kss1(K42R Q45P)], Kss1(T183A Y185F) [TA/YF; YCpU-kss1(T183A Y185F)], Kss1(S303A) (SA; pRC136), Kss1(S303D) (SD; pRC137), or Kss1(S303E) (SE; pRC138). Transformants were grown on SCD–Ura plates, replicated to YPD, and assessed for invasive growth.