Podoplanin is expressed in FLS in areas of synovial transformation. Immunohistochemistry of (A and B) frozen and (C-J) paraffin-embedded human synovial tissue from patients with rheumatoid arthritis (RA) using antibodies against (A and C) podoplanin (D2-40), (B) CD90 (AS02) and (D) cadherin-11 (3B2H5) (arrowhead). Double immunofluorescence staining analysed by confocal microscopy showing, in green, (E) podoplanin 18H5 and (F-J) podoplanin D2-40, and in red, (E) cadherin-11 (3B2H5), (F) CD68 (KP1), (G and overview in H) E-cadherin (H-108), (I) α-smooth muscle actin (α-sma) (PA1-37024) and (J) matrix metalloproteinase 9 (MMP-9). (E) Note colocalization of podoplanin and cadherin-11 (arrowhead). L, lumen.