Probable RNA polymerase II subunit B1 C-terminal domain (CTD) phosphatase that regulates RNA polymerase II transcription. May have functional redundancy with RTR1. H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Present with 1050 molecules/cell in log phase SD medium. Belongs to the RPAP2 family.