Fig 2: (a,b) Western blot detection of PEDF and thrombospondin‐1 in cell conditioned medium. 30 μg proteome were used with a 12.5% reducing SDS‐PAGE. (c) Western blot detection of LAP/TGFβ‐1 in cell conditioned medium. 8 μg proteome were used with a 12.5% reducing SDS‐PAGE. The primary antibody was directed against the LAP domain (prodomain). In line with previous reports (Dubois et al., 1995), the ∼55 kDa band is thought to represent proTGFβ‐1 whereas the predominant ∼40 kDa band is thought to represent LAP. The elevated size in comparison to the primary sequence is thought to stem from glycosylation (Brunner et al., 1992; Dubois et al., 1995). (d) Western blot detection of mature TGFβ‐1 (disulfide linked dimer) in cell conditioned medium. 30 μg proteome were used with a 12.5% non‐reducing SDS‐PAGE. The primary antibody was directed against the actual TGFβ‐1 domain. In addition, N‐terminal degradomics showed TGFβ‐1 activation (see corresponding section). (e) Western blot detection of L1CAM in cell conditioned medium (CCM) and total cell lysate, including cell surface proteins. 8 μg (CCM) and 12 μg proteome (total cell lysate), respectively, were separated with a 7.5% reducing SDS‐PAGE. The molecular weight of 220 kDa for L1CAM is higher than expected but in line with previous reports (Li and Galileo, 2010).