AS-DACA resistance in rhabdomyosarcoma cells. (A) Structure of AS- DACA. (B) MTT cell viability results presented as cytotoxicity curves for AS-DACA in RD and RH30. (C) Derivation of the AS-DACA-resistant RMS cell line, Res30. Dose- response curves from MTT cell viability assays performed at various stages in the development of AS-DACA-resistant RH30 cells. (D) Cytotoxicity curves of (i) 9-amino- DACA, (ii) doxorubicin, and (iii) mitoxantrone in Res30 cells. Error bars are SEM for independent experiments performed in triplicate.