A metabolism-focused CRISPR screening using Jurkat leukemia cells revealed that the loss of either of two mitoferrin isoforms, MFRN-1 (SLC25A37) or MFRN-2 (SLC25A28), sensitizes cells to GPX4 inhibition–induced ferroptosis [20], which suggests that the mitochondrial import of iron (perhaps because it is sequestered in the mitochondrial matrix) is essential to protecting cells from ferroptosis. Here, GPX4 is linked to leukemia.