DUSP6 and neoplasm: DUSP6 levels were effectively inhibited for 24–48 h after the treatment and pathway inhibition was tightly associated with concentrations of RMC-7977 in tumours (Fig. 3a,b; half-maximal effective concentration (EC50) = 142 nM in Capan-1 CDX tumours), indicating that the local drug concentration is a critical determinant of biochemical activity.