MMAE (monomethyl auristatin E) is an antimitotic agent that binds to tubulin and inhibits the assembly of microtubules. Mc-VC-PAB-MMAE is a thiol reactive derivative of MMAE that containing a cathepsin cleavable valine-citruline p-aminobenzylcarbamate linkage. Mc-VC-PAB-MMAE is used to prepare antibody-drug conjugates, such as brentuximab vedotin (Seattle Genetics).