SW-1116 cells stably expressing ASS1WT, or ASS1 K234R and LOC113230 or not were treated with MG132 (5 μM) for 12 hrs. Cell lysates were immunoprecipitated (IP) assays were performed with α-Flag antibody. The co-eluted proteins were detected by western blot assays with ubiquitin (Ub) and α-Flag antibodies, respectively. 