CBX4 and lung adenocarcinoma: To evaluate the impact of CBX4 knockdown and overexpression on lung adenocarcinoma cell metastasis in vivo, we injected A549 cells stably expressing control shRNAs, CBX4 shRNAs, empty vector, or Flag-CBX4 into the tail veins of 4-5-week-old NOD/SCID mice.