UNC13B and mastocytoma: The Munc13-4wt, Munc13-4Cys112Ser, Munc13-4Val781Ile, Munc13-4Ile848Leu, Munc13-4Ala995Pro, Munc13-4Ile848Leu/Ala995Pro, and Munc13-4Pro271Ser constructs were transfected into the HMC-1 mastocytoma cell line.