PDE4B and cancer: A series of PDE4 inhibitors, such as roromeste, oglemilast, GSK256066, CHF6001, YM976, GS-5759, etc., have been in development to improve the selectivity of drugs to reduce adverse reactions, such as inhibitors that specifically target PDE4B in the treatment of inflammation (Tralau-Stewart et al., 2011), colorectal diseases, and cancer (Nose et al., 2016)have shown a promising therapeutic future.