CBS and neoplasm: Our metabolic model simulations predict that malignant cells are selectively vulnerable to the knockdown of the cysteine transporter complex that consists of the transporters SLC3A2 and SLC7A11, because the enzyme for cysteine de novo biosynthesis, cystathionine-beta-synthase (CBS), is selectively depleted in malignant cells (Fig. 2B, CBS expression; Figure S2A, bar plot of CBS-expressing, i.e., expression level >0, locations in tumor and non-tumor regions).