FOS and melanoma: Both cell lines have been widely used to study melanoma plasticity (Carreira et al., 2006; Cheli et al., 2011; Miskolczi et al., 2018; Ohanna et al., 2011; Strub et al., 2011), and because the respective transcriptional states linked to MITF in melanocytic 501mel cells or related to SMADs and AP1 in mesenchymal WM266‐4 cells are maintained when in culture (Figure S1a), they represent reliable models for each individual transcriptional phenotype.