Fig. 4

MEX3C mediated RUNX3 ubiquitination and degradation. A, B Transduction of A549 and H1299 cells with overexpressed MEX3C (OE-MEX3C) or si-MEX3C. Overexpression efficiency of MEX3C in A549 and H1299 cells using qRT-PCR (A) and western blotting (B). C, D By using qRT-PCR and western blotting, the mRNA (C) and protein (D) levels of RUNX3 were determined in MEX3C knockdown or overexpression A549 and H1299 cells. E A549 and H1299 cells were transduced with OE-MEX3C and subsequently grown with MG132 at a concentration of 10 μmol/L for 24 h. The presence of RUNX3 protein was determined using western blotting. F, G The interaction between MEX3C and RUNX3 was detected by Co-IP assay. H In vivo ubiquitination assay of HEK293 cells transfected with plasmids expressing Flag-tagged RUNX3, Myc-tagged MEX3C, and HA-tagged ubiquitin. I A549 and H1299 cells were transduced with OE-MEX3C. The ubiquitination level of RUNX3 was determined by ubiquitination assays. Bars represent mean ± SD from 3 independent experiments. **P < 0.01. ns, no significance