PDE4D and pachyonychia congenita: We also detected the protein levels of PDE4D and phosphorylation levels of ERK and AKT in CRC patients, found the levels of PDE4D, p‐ERK and p‐AKT was higher in MLM samples than that in PC samples, the p‐ERK and p‐AKT exhibited significant correlations with the expression of PDE4D (Figure 5L and M).