TNF and type 1 diabetes mellitus: To this end, MIN6 β-cells were pretreated with verapamil or left untreated (control) for 24 h, followed by a 24 h challenge with T1D-cytomix containing IL-1β (50 ng/mL), TNF-α (50 ng/mL), and INF-γ (100 ng/mL) to mimic the T1D pancreatic cytokine microenvironment in a clinical setting, and cell viability was determined using an MTT assay.