Toxic component of a type II toxin-antitoxin (TA) system (PubMed:25391136, PubMed:27672196). Acts as an RNase (Probable). Its toxic effect is neutralized by cognate antitoxin VapB1 (PubMed:25391136, PubMed:27672196) but not by non-cognate antitoxin VapB2 (PubMed:25391136, PubMed:27672196). Forms a complex with VapB1 (PubMed:27672196). More highly expressed in early growth phase, expression decreases as cell density decreases. Part of the vapB1-vapC1 operon. Belongs to the PINc/VapC protein family.