PPP1R1B encodes protein phosphatase 1 regulatory inhibitor subunit 1B, primarily functioning as an inhibitor of protein phosphatase 1 (PP1) 1. The gene produces two protein products: Darpp-32 (dopamine and cAMP-regulated phosphoprotein, 32 kDa), whose phosphorylation is regulated by cAMP in dopamine-responsive brain tissues, and t-Darpp (truncated Darpp-32), lacking the PP1-inhibitory domain 1. Beyond its classical role in dopaminergic signaling, PPP1R1B functions as a long noncoding RNA (Ppp1r1b-lncRNA) that promotes myogenic differentiation by inhibiting polycomb repressive complex 2 (PRC2) at myogenic transcription factor promoters 2. In cancer pathophysiology, PPP1R1B upregulation correlates with metastatic progression. Loss of HIF1A in pancreatic cancer increases PPP1R1B expression, which promotes p53 degradation by stabilizing MDM2 phosphorylation, enhancing invasion and metastasis 3. PPP1R1B overexpression in breast, gastric, and cholangiocarcinoma activates AKT signaling, promoting cell survival and, in Her2-positive breast cancers, causing trastuzumab resistance 1. In intrahepatic cholangiocarcinoma, elevated PPP1R1B promotes proliferation, migration, and invasion through PI3K/AKT pathway activation 4. In neuropsychiatric contexts, PPP1R1B variants influence brain connectivity during emotional learning, affecting dopaminergic and glutamatergic pathways 5. While genetic association studies in schizophrenia populations showed no significant allelic associations 6, PPP1R1B remains functionally relevant to neurotransmitter signaling dysregulation in psychiatric disorders.