MAP2K1 and melanoma: We found that 6/6 PLX4720-resistant melanoma cell cultures (group 1) showed strong (i.e. IC50 > 1 μM) or intermediate (i.e. IC50 > 0.1 μM) cross-resistance to MEK1/2 and PI3K/mTOR inhibitors, and 11/13 cultures in group 2 (intermediate resistance to PLX4720) showed also strong or intermediate cross-resistance to PI3K/mTOR inhibitors (Figure 3A).