Similarly, AUY922 did not alert the expression of MEK, another client protein of HSP90 [34], in mutant BRAF colon cancer cells (Figure 2A), whereas it reduced, albeit moderately, MEK expression in wild-type BRAF colon cancer cells (Figure 2A), suggesting that AUY922-induced transient inhibition of MEK/ERK activation in mutant BRAF colon cancer cells is also primarily due to blockade of upstream signals. This evidence concerns the gene BRAF and colonic neoplasm.