Using trans-activation assays two isoforms of APK; APK1 and APK2 are regulated by both classes of GSL MYB transcription factors; whereas two ATPS genes; ATPS1 and ATPS3 are differentially regulated by these two groups of MYB factors. The adenosine 5-phosphosulfate reductases APR1; APR2; and APR3 which participate in primary sulfate reduction are also activated by the MYB factors (Yatusevich et al. 2010)  