ICAM1 and breast carcinoma: To determine whether FBXO4 degrades ICAM-1 by specific ubiquitination, the ICAM-1 and FBXO4 interaction was tested in metastatic breast cancer cells by co-immunoprecipitation (IP) and western blot analysis following treatment with a proteasome inhibitor (Figure 2E-2F); the results were confirmed in HEK293T cells (Figure 2G-2H).