Polyubiquitination analysis upon GSK3 inhibition in HeLa cell extracts

HeLa cell extracts with or without GSK3 enzyme inhibition were assayed using protein microarrays in order to detect GSK3-dependent changes in protein polyubiquitination. HeLa lysates in triplicates were supplemented with ubiquitin and incubated on protein microarrays (ProtoArray 5.0; Invitrogen) in the presence or absence of the GSK3 inhibitor SB-216763. Polyubiquitination of the arrayed proteins was detected using specific antibodies. ProtoArray 5.0 contains over 9,000 full-length human proteins purified and arrayed in duplicate under native conditions to maximize functionality.