RPRD1A and RPRD1B associate with RNAPII phosphatase directly and interact with CTD heptapeptide repeats to recruit RNAPII for dephosphorylation of phosphor-S5 [18,19] Recently, an enhanced expression of CREPT, also known as RPRD1B or C20orf77, is reported in many human tumors, including gastric cancer, endometrial cancer, and colorectal cancer [20]. Here, RPRD1B is linked to endometrial cancer.