PDE4D and colorectal cancer: In addition, PDE4D has been found to serve as an oncogene regulated by miRNAs to promote tumor progression in various human cancers, such as miR-494-PDE4D in gastric cancer (20) and miR-203a-3p-PDE4D and miR-139-5p-PDE4D in colorectal cancer (21, 22).