PRPF4 (pre-mRNA splicing tri-snRNP complex factor) is a core protein component of the U4/U6-U5 tri-snRNP complex essential for spliceosome assembly and pre-mRNA splicing 1. The protein maintains tri-snRNP structural integrity through interactions with PRPF3 and Cyclophilin H, and directly interacts with peptidyl-prolyl isomerase H (PPIH) via bipartite binding sites at its intrinsically disordered N-terminus 2. Beyond splicing, PRPF4 regulates U4/U6 di-snRNP stability and influences cell survival and apoptosis pathways 1. Clinically, PRPF4 mutations cause autosomal dominant retinitis pigmentosa (RP70) through haploinsufficiency and dominant-negative mechanisms 1, with loss-of-function variants disrupting PRPF4-PRPF3 binding and tri-snRNP integration 3. The tissue-specific retinal phenotype despite ubiquitous splicing protein expression remains unexplained 4. Beyond RP, PRPF4 is upregulated in multiple cancers, including glioblastoma, breast cancer, and colorectal cancer 567. In cancer contexts, PRPF4 knockdown reduces proliferation, migration, and invasion while inducing apoptosis via p38 MAPK pathway suppression 56, suggesting PRPF4 as a potential therapeutic target for cancer treatment 7.