Novel CD9-targeted therapies in gastric cancer

Table 1 CD9 associated with partner proteins

Partner protein	Function	Ref.
EWI-2	Modulates integrin-dependent cell motility, morphology and/or spreading	[5-6,8,44,45,50]
EWI-F	Functions unknown	[5-6,8,46,47]
Integrin β1	CD9 modulates integrin-dependent cell morphology, cell migration, signaling and adhesion strengthening	[5,11]
Other tetraspanins (e.g., CD81, CD151)	Form TEMs	[7,8]
Claudin-1	CD9 stabilizes expression of non-junctional Claudin-1	[10]
EGFR	CD9 enhances the internalization of EGFR and reduces EGF-EGFR-induced signals	[11]
HB-EGF	CD9 upregulates both diphtheria toxin binding and mitogenic functions of HB-EGF	[23,24]
PKC isoforms	Contribute to signaling and tumor-suppressor functions	[29]
Type II PI4K	Contribute to signaling and tumor-suppressor functions	[30]

EGFR: Epidermal growth factor receptor; HB-EGF: Heparin-binding epidermal-growth-factor-like growth factor; PKC: Protein kinase C; TEMS: Tetraspan-enriched microdomains.