sentence: The possibility that xrn4 mutants are defective in the LER pathway is particularly intriguing.In agreement with a role of XRN4 in the LER , mRNA levels of two well-known sugar-responsive marker genes , ATL8 and bZIP1 , were elevated to a higher extent in xrn4 compared to the WT in response to 24-h dark treatment ( Figure 6D ) .