PADI2 can also citrullinate R1810 (cit1810) at RNAP2-CTD (RNA polymerase II), promote the interaction with the P-TEFb (positive transcription elongation factor b) complex, lead to the release of RNAP2, and promote the transcription of cell cycle genes and the proliferation of breast cancer cells (62). The gene discussed is PADI2; the disease is breast carcinoma.