Treatment selects resistant cell lineages

Could treatment meant to remove atypical cells leave reconstructed skin able to regrow faster after the drug is withdrawn? This proposed mechanism says repeated treatment may enrich a rare resistant cell lineage, descendants of one founder cell that survive the drug. Its defining prediction: move equal numbers of survivors into fresh untreated skin, and the resistant lineage should still repopulate faster while keeping its pretreatment division rate. Sustained growth begins only when production of self-renewing basal cells exceeds losses from death and terminal differentiation. Testing requires lineage labels and separate records of division, differentiation and death before crowding limits growth. Functional donor DNA and a transferable signal in cell-free medium are rival explanations.