The overexpression of H2S-producing enzymes (CBS, but also 3-mercaptopyruvate sulfurtransferase, 3-MST and cystathionine γ-lyase, CSE) has been detected in many different types of cancer; known cancer-supporting roles of H2S include the stimulation of cellular bioenergetics, the induction of proliferative and cytoprotective pathways, the stimulation of tumor angiogenesis, the promotion of epithelial to mesenchymal transition (EMT), protection against immune-cell-mediated elimination, maintenance of cancer cell stemness and others (reviewed in [3]). Here, MPST is linked to cancer.