To test whether digitoxin plus MEK inhibitor would prolong the survival of xenografted mice with metastatic disease we subcutaneously injected melanoma cells derived from two patients (M491, M481), allowed tumours to grow to 2 cm in diameter, then surgically removed the melanomas and initiated treatment with digitoxin and/or MEK inhibitor (Fig. 2b). Here, MAP2K7 is linked to melanoma.