Profiling of the secretome of isogenic immortalised GCT cell lines revealed that extracellular matrix (ECM) ligands such as collagens (Collagen Type VI Alpha chain 1/3, COL6A1/3 and Collagen Type V Alpha chain 2, COL5A2) and proteoglycans (Biglycan, BGN), which are predicted to interact with integrin receptors on monocyte/macrophages (Integrin Subunit Beta 2, ITGB2) and osteoclasts (Integrin Subunit Alpha V, ITGAV) respectively, were differentially secreted by H3.3-G34 mutant cells. This evidence concerns the gene COL6A1 and granular cell tumor.