The chemical compound PMA is a potent stimulator of the epithelial-mesenchymal transition in epithelial cells. The activity of two of the following types of proteins is typically up-regulated in epithelial cells treated with PMA, while that of the other two is mainly down-regulated. Choose the two proteins whose activity you think is stimulated by PMA. Your answer would be a two-letter string composed of letters A to D only in alphabetical order, e.g. BC.
(A) Cadherin
(B) Connexin
(C) Matrix metalloprotease
(D) Integrin