Other examples include motexafin gadolinium (an electron acceptor that increases superoxide production; used in the treatment of breast cancer and malignant melanoma) [162], arsenic trioxide (inhibits SOD and TrxR; used in the treatment of relapsing acute myeloid leukemia) [135], and imexon (disrupts GSH activity, causing depletion of GSH pool; used in the treatment of ovarian cancer, multiforme glioblastoma, and multiple myeloma) [135,162]. Here, SOD1 is linked to plasma cell myeloma.