Export of 5-MTP by fibroblasts inhibits cancer cell COX-2 overexpression by blocking p300 histone acetyltransferase (HAT) and NFκB activation [126,127], inhibits A549 cancer cell migration and invasion, and retards A549 cancer growth and metastasis in a murine xenograft tumor model, possibly through COX-2 suppression [126]. Here, EP300 is linked to cancer.