SPP1 and neoplasm: Tumor-derived SPP1 achieves this transition by engaging CD44 (bSE = 2.5) and ITGAV (bSE = 2.2)/ITGB3 (bSE = 2.7) on the fibroblast surface, which mediates signaling via AKT (AKT1 and AKT3) and ERK (ERK2 = MAPK1) to induce TWIST1 (bSE = 2.5)-dependent gene expression in BC [61].