Remarkably, knockdown of G9a had pronounced effects on the expression of important cancer-associated proteins including HP1α encoded by Chromobox 5 (CBX5), ATP-binding cassette sub-family G member 2 (ABCG2), angiopoietin-like 4 (ANGPTL4), APC2, urokinase plasminogen activator (u-PA), Junctophilin-3 (JPH3), Talin 1 (TLN1), and telomerase reverse transcriptase (TERT) etc. that are involved in cell proliferation, invasion, and metastasis, drug resistance. This evidence concerns the gene APC2 and cancer.