RBX1 and lung carcinoma: Using CENP-F as a G2/M cell marker, we observed a strongly negative correlation between the expression levels of RBX1 and EXO1 proteins in multiple cell types, including human cervical carcinoma HeLa, breast adenocarcinoma MCF7, lung carcinoma A549, and osteocarcinoma U2OS cells (Fig. 2a, b).