HUVECs adhesion assay of P2 and PB-TUP-P2. Polystyrene 96-well cell culture plates were coated with P2 or PB-TUP-P2 at a concentration of 75 μM and saturated with 1% BSA. HUVECs were seeded at a density of 2 × 104 cells per well. The adhered cells were measured by cck-8 kit. The number of HUVECs bound to PB-TUP-P2-coated wells showed a very significant difference from that of P2-coated wells. Fusion with PB-TUP did not affect the interaction between P2 and HUVECs.