RSRP1 and glioblastoma: In glioblastoma, arginine/serine-rich protein 1 (RSRP1) catalyzes PARP6 exon 18 skipping, generating the truncated oncogenic form of PARP6 (PARP6-s), which lacks the catalytic triad of residues essential for MARylating activity (Fig. 5A).