OLC1 protein is degraded by the APC/c. (A) Analysis of the OLC1 protein sequence indicated that it contains a destruction box at the site of amino acids 12–20, which may be recognized by APC/c. (B) To investigate whether OLC1 may bind directly to the components of the APC/c, KYSE150/GFP-OLC1 cells were collected, lysed and subjected to IP. The presence of actin, OLC1 and APC2 in the immunocomplex were verified. (C) Different concentrations (2, 4 and 8 µg) of Myc-Cdh1/Cdc20 expression or mock vectors were transiently transfected into H1299 cells for 48 h. Then OLC1, Myc-Cdh1 and Myc-Cdc20 protein expression were evaluated. Actin was included as a loading control. Different concentrations (20, 50 and 100 nM) of (D) Cdh1 or (E) Cdc20 or mock siRNA were transiently transfected into H1299 cells for 48 h. Then OLC1, Cdh1 and Cdc20 protein expressions were evaluated. Actin was included as a loading control. OLC1, overexpressed in lung cancer 1; APC/c, anaphase-promoting cyclosome complex; IP, immunoprecipitation; Cdh1, cadherin 1; Cdc20, cell-division cycle protein 20; siRNA, small interfering RNA.