Toxic component of a type II toxin-antitoxin (TA) system. Upon expression in E.coli inhibits growth in liquid culture. Its toxic effect is neutralized by coexpression with antitoxin VapB1. Degrades RNA but not ss- or ds-DNA in vitro, degradation is inhibited by VapB1 antitoxin. Forms a complex with VapB1. More highly expressed in early growth phase, expression decreases as cell density increases. Part of the vapB1-vapC1 operon. Belongs to the PINc/VapC protein family.