Previous studies have shown that PRMT5 undergoes various PTMs, including phosphorylation and arginine methylation. In our investigation of PRMT5's PTMs, we detected elevated phospho-Ser/Thr levels of PRMT5 in CDDP-resistant ovarian cancer cells Hey compared to their parental counterparts by co-immunoprecipitation of PRMT5. To further identify the phosphorylation sites that may be involved in the CDDP resistance mechanism, we identified the phosphorylation modification sites of PRMT5 by mass spectrometry.