P110 inhibitor, a 7‐amino acid peptide representing a homology sequence between Drp1 and Fis1, is delivered across cell membranes and was shown previously to cross the blood–brain barrier with the TAT47–57 carrier peptide (Guo et al, 2013), as do other short TAT47‐57‐conjugated peptides [e.g., Bright et al (2004), Qi et al (2008)]. We previously showed that P110 treatment selectively inhibits Drp1 interaction with Fis1; P110 does not affect Drp1 interaction with any other mitochondrial adaptors of Drp1 or with the mitochondrial fusion proteins OPA1, Mfn1, or Mfn2 (Qi et al, 2013). Importantly, P110 selectively inhibits pathological, but not physiological mitochondrial fission and fragmentation (Qi et al, 2013), which may explain why even a 5‐month treatment of wild‐type mice causes no adverse effects (Appendix Fig S1).