PTEN and neoplasm: We assessed the expression levels of markers associated with the MAPK pathway, such as PDGFRα, cRaf, ERK, p38 and JNK, and markers associated with the PI3K/Akt pathway, such as PTEN, PI3Kp85, PDK1, Akt, and mTOR, to determine which pathway was responsible for DXR-induced drug resistance and tumour growth in the tumour-bearing mouse model.