The proposed mechanisms of polymyxin-induced apoptotic cell death in renal tubular cells. AIF, apoptosis-induced factor; CAT, catalase; CDK2, cyclin-dependent kinase 2; cytC, cytochrome C; MAPK, mitogen-activated protein kinase; MDA, malondialdehyde; MR, endocytic receptor megalin; OCTN1, organic cation transporter 1; SOD, superoxide dismutase; tBid, truncated Bax-inhibiting peptide . Reproduced with permission (Dai et al., 2014). Copyright © American Society for Microbiology.