FN1 and chronic myelogenous leukemia, BCR-ABL1 positive: To find the role of BCR/ABL in sustaining the mesenchymal phenotype of CML cells, we knocked down the expression of BCR/ABL by RNA interference (RNAi) (Fig. 6A) and examined the expression of mesenchymal markers such as fibronectin, N-cadherin E-cadherin and vimentin in K562 cells.