siRNA-mediated silencing of UBB and UBC, alone or in combination, led to a marked decrease in their respective mRNAs (p < 0.001 for UBB silencing with siUBB in both cell lines; p = 0.002 and p = 0.003 for UBC silencing with siUBC in 23132/87 and MKN45, respectively; p = 0.007 for UBB and p = 0.029 for UBC silencing with siUBB+siUBC in 23132/87; p = 0.009 for UBB and p = 0.013 for UBC silencing with siUBB+siUBC in MKN45), with UBB knockdown being more effective than UBC knockdown in both GC cell lines (Figure 4A,B). This evidence concerns the gene UBC and gastric cancer.