PDE4A and neoplasm: In contrast to these finding, Kim et al. [132], in agreement with other studies, found that aberrant PDE4D expression contributed highly to the malignant phenotype of the colorectal cancer cells DLD-1 by targeting the mTOR-Myc axis; treatment with PDE4 inhibitors suppressed mTOR/Myc signalling and tumour effects; similar positive consequences were obtained when the mTOR inhibitor rapamycin was used.