ASMA staining is observed in SSc fibrocytes, but not normal fibrocytes, and is blocked by CSD and Cav-BC. PBMC were incubated for fibrocyte differentiation in vitro on coverslips as described in the Methods in the presence of the indicated peptides at 0.1 μM, then stained for collagen I and ASMA and counterstained with the nuclear stain DAPI. The Antennapedia Internalization Sequence alone was routinely used as the Control peptide; when tested scrambled CSD attached to the Antennapedia Internalization Sequence gave similar results. Note the increased number of fibrocytes in SSc cultures, the inhibition of fibrocyte differentiation by CSD and Cav-BC in both SSc and normal cultures, the expression of ASMA in SSc fibrocytes but not in normal fibrocytes, the inhibition of ASMA expression by CSD and Cav-BC, and the similar levels of collagen I expression in fibrocytes in all cases. Similar results were obtained in four independent experiments.