In some tissues, such as ovary [19, 30], breast [20, 31] and lung (adenocarcinoma) [32], this glypican is downregulated, acting as a tumor suppressor, whereas in other tumors, it is overexpressed and functions as an oncoprotein, as observed in liver [33–35], lung (squamous cell carcinoma) [32, 36], melanoma [18] and embryonal tumors [37]. Here, GPC1 is linked to squamous cell carcinoma.