Thus, the association of nuclear β-catenin with the T cell factor (TCF)/lymphoid enhancer factor (LEF) family of transcription factors may up-regulate the expression of several gene products such as c-Myc, cyclin D1, gastrin, COX-2, MMP-7, uPA receptor, CD44 and P-glycoprotein that are involved in colorectal cancer development and treatment resistance (Figure 2) [163]. The gene discussed is PTGS2; the disease is colorectal cancer.