*3.1. Correlation between ELISA and Luminex Immunoassays*

In order to evaluate the correlation between ELISA and Luminex immunoassays, pleural effusion levels of shed SDC-1, Mesothelin and VEGF were measured independently by both immunoassays. High correlation between immunoassays was observed (Figure 1). We found statistically significant linear correlation between shed SDC-1 (*p* = 0.0001, *r* = 0.8), Mesothelin (*p* = 0.0001, *r* = 0.6) and VEGF (*p* = 0.0001, *r* = 0.9) that measured by ELISA comparing with the Luminex assay, suggesting that Luminex assay can be used in the clinic.

**Figure 1.** Correlation between enzyme-linked immunosorbent assay (ELISA) and Luminex. (**A**) Correlation between shed Syndecan-1 (SDC-1) level in pleural effusion measured by ELISA and Luminex. (**B**) Correlation between VEGF level in pleural effusion measured by ELISA and Luminex. (**C**) Correlation between Mesothelin level in pleural effusion measured by ELISA and Luminex. Spearman correlation analysis was used to assess the correlation between these two immunoassays.
