Significance This work provides biophysical insights into how BRAF mutant melanoma cells adapt to the stress of MAPK inhibition via a series of reversible phenotypic transitions toward drug-tolerant or drug-resistant cell states enriched for neural-crest factors and mesenchymal signatures. This adaptation is influenced by cell phenotype-specific drug selection and cell state interconversion, but not selection of genetically resistant clones. A panel of functional proteins, analyzed at the single-cell level, pointed to signaling network hubs that drive the initiation of the melanoma cell adaptive transition. Targeting those hubs halted the transition and arrested resistance development.