(A) Western-blot analysis of fibulin-4 in CHO-cell conditioned medium. Fibulin-4 was detected only in the conditioned medium (lane FB4) of fibulin-4-overexpressing cells and not in the conditioned medium (lane C) of control cells. (B, C) Expression of tropoelastin and GAPDH mRNAs in the WBS fibroblast cultures in DMEM with 2 % FBS (lane 1), in conditioned medium from control CHO cells mixed with equal volume of DMEM with 2 % FBS (lane 2) or in conditioned medium from CHO cells overexpressing fibulin-4 cells mixed with equal volume of DMEM with 2 % FBS (lane 3). Fibroblasts exposed to fibulin-4-overexpressing conditioned medium demonstrated a significantly higher level of tropoelastin mRNA. The experiment was repeated three times. **P < 0.0001 compared with lane 1 or lane 2. (D) WBS fibroblasts maintained for 5 days either in DMEM containing 2 % FBS or in the medium consisting of equal volumes of DMEM and conditioned medium from control CHO cell cultures did not form elastic fibres (D, panel 1) and (D, panel 2). In contrast, the parallel cultures of WBS fibroblasts maintained in medium consisting of equal volumes of DMEM and conditioned medium from cultures of CHO cells overexpressing fibulin-4 (final concn. of fibulin-4: 10 ng/ml) demonstrated a significant formation of immunodetectable elastic fibres (D, panel 3).