Fig. 4. Effect of csx1Δ mutation on the expression of stress transcription factors. (A) Northern blot of atf1⁺, pcr1⁺, pap1⁺ or prr1⁺ mRNAs after treatment of wild-type or csx1Δ cells with 1 mM H₂O₂. Aliquots were collected at the indicated times after addition of H₂O₂. (B) Northern blot of atf1⁺ mRNA after treatment of wild-type or csx1Δ cells with 0.3 mM H₂O₂. Aliquots were collected at the indicated times after addition of H₂O₂. (C) Western blot showing Atf1-HA in wild-type or csx1Δ cells after treatment with 1 mM H₂O₂. (D) Northern blot of atf1⁺ mRNA after treatment of wild-type or csx1Δ cells with 0.8 M KCl. Aliquots were collected at the indicated times after addition of KCl. (E) Northern blot of atf1⁺ mRNA after treatment of wild-type, spc1Δ or csx1Δ spc1Δ cells with 1 mM H₂O₂.