The “proliferative”—also referred to as the “melanocytic”—state is characterised by medium to high expression of the melanocyte-inducing transcription factor, also known as microphthalmia-associated transcription factor (MITF) [29], while the “invasive”—also referred to as “undifferentiated” and “mesenchymal-like”—state is characterised by low MITF and high expression of AXL [30], a gene coding for a tyrosine kinase receptor [31], which is emerging as a key player in progression and metastasis of several cancer types [32]. This evidence concerns the gene AXL and cancer.