The effects of CPT on deposition of collagen types I (a), III (b), and VI (c) and elastin (d) in SSc and healthy control fibroblasts. Fibroblasts were grown to confluence in 96-well plates and then incubated for 24 h with CPT in DMEM/1% FBS. In control wells ('None'), the CPT was omitted. ELISA was performed on the cell and matrix layers with appropriate antibodies as described in the Patients and methods section. Bars show the relative amounts of collagen types I, III, and VI (a–c) from 11 pairs of SSc and healthy fibroblast cell lines and of elastin (d) from from four pairs of SSc and healthy fibroblast cell lines. All experiments were done in triplicate. CPT = camptothecin; FBS = fetal bovine serum; SSc = systemic sclerosis. *P < 0.05, **P < 0.005.