CD44 and neoplasm: HA is widely present in the ECM of higher animalsand plays a critical role in cell–ECM interactions, wound healing,cell differentiation, and cell motility. In addition, HA is also a key component of stem cell and CSC niches,interacts with CD44, a receptor overexpressed in various tumors, andcorrelates with tumor progression and metastasis., HA and collagen form the main ECM in the tumor niche, suggestingthat mechanically tunable hydrogels composed of methacrylated hyaluronicacid (HAMA), methacrylated collagen (ColMA), and collagen can effectivelyrecapitulate metastatic behaviors.