APCDD1 and melanoma: For example, when melanoma cells were treated with MAPKi for a long period, they underwent global epigenetic reprogramming and upregulated the expression of drug resistant genes such as APC down-regulated 1 (APCDD1), epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor beta (PDGFRB) and neuregulin 1 (NRG1).