KCNMB4 encodes the beta-4 regulatory subunit of large-conductance calcium-activated potassium (BK/KCa1.1) channels, which modulates channel gating kinetics and calcium sensitivity. As a regulatory component, KCNMB4 decreases calcium sensitivity and gating kinetics while providing fast deactivation kinetics, and confers resistance to charybdotoxin [UniProt]. The β4-subunit is highly expressed in ocular tissues, particularly the conventional outflow pathway, where it significantly regulates aqueous humor outflow facility and intraocular pressure 1. KCNMB4 expression has been implicated in multiple pathological contexts. In osteosarcoma, recurrent KCNMB4-CCND3 fusion genes promote tumor cell motility 2. The gene contributes to paclitaxel resistance in nasopharyngeal carcinoma through PRMT5-mediated upregulation via histone methylation 3. KCNMB4 expression is also upregulated in SARS-CoV-2 infected cells, potentially through a competitive endogenous RNA mechanism involving viral circ_3205 and miR-298 4. Additionally, KCNMB4 is involved in neuroblastoma pathogenesis and action potential regulation 5. The clinical significance extends to potential therapeutic targeting for glaucoma treatment through modulation of intraocular pressure and as a biomarker in various cancers where it correlates with chemoresistance and tumor progression.