CCN2 and head and neck squamous cell carcinoma: Importantly, CTGF levels in MSC-CM did not increase after culturing of HNSCCs, and MSC mono-cultures exhibited similar CTGF levels as HNSCC-MSC co-cultures (also recognizing that two types of cell culture media were used), suggesting that CTGF levels were almost exclusively and constitutively secreted by MSCs, and the presence of HNSCCs did not stimulate CTGF secretion.