CASP4 and neoplasm: As a protein arginine methyltransferase, PRMT5 catalyzes the methylation of targeted proteins, and either inhibits the transcription of tumor suppressors (such as p53, E2F-1, ST7, NM23, and CASP4) to promote tumor occurrence, (Pal et al., 2004; Zhu and Rui, 2019) or is involved in the activation of transcription factors.