(A) The PSR induces the cleavage of PRORALF23-GFP into mature RALF23-GFP. The 35S promoter-driven RALF23-GFP line was grown in either HP or LP media for 5 days and roots were harvested. Premature and mature RALF23 levels were determined with anti-GFP. β-actin was used as a loading control. Data information: All experiments were repeated three times with similar results. 