ERBB2 and cancer: By contrast another paper implicated the loss of CERT in the progression of triple-negative breast cancer cells, which express cytokeratins 5/6, 14, and 17, lack ER/PR expression and ErbB2/HER2 amplification/overexpression and are especially refractory to treatment [93], thus suggesting that the role of CERT in chemoresistance and cancer progression is still controversial and could strongly depend on the global cancer gene expression profile.