PDE4B and melanoma: Based on these results, we narrowed down our focus to 10 genes (NMI, SNTB2, SLC1A4, PDE4B, CLEC2B, IFI27, COL1A2, MAF, LAMP3 and CCDC69) related to the differential expression of M1 and M2 macrophages during melanoma metastasis, with this study representing the first time that such an experiment took place.