VSPPLTLGQLLS is a small peptide FGFR3 inhibitor, peptide P3, inhibits FGFR3 phosphorylation. VSPPLTLGQLLS inhibits 9-cisRA-induced tracheal lymphangiogenesis and blocks lymphatic endothelial cell (LEC) proliferation, migration, and tubule formation. Form:Solid IC50& Target:FGFR3|K650M-FGFR3|K644E FGFR3 In Vitro:VSPPLTLGQLLS (5 μM and 10 μM; 24 h and 48 h) inhibits human primary lymphatic endothelial cell (LEC)s proliferation, migration, and tubule formation. VSPPLTLGQLLS shows effective inhibition in FGFR3 phosphorylation in LECs and also demonstrated to be effective in ATDC5 chondrogenic cells, 293T cells, explanted metatarsal bone cultures, and an in vivo mouse model of thanatophoric dysplasia II[2] . VSPPLTLGQLLS (10 μM; 6 h) inhibits tyrosine kinase activity of FGFR3 and its typical downstream molecules, extracellular signal-regulated kinase/mitogen-activated protein kinase. VSPPLTLGQLLS (0, 1, 10, and 50 μM; 24 h and 3 or 7 days, respectively) also promotes proliferation and chondrogenic differentiation of cultured ATDC5 chondrogenic cells. VSPPLTLGQLLS (10 μM; 0-60 min) inhibits the ERK/MAPK pathway in FGFR3-expressing chondrocytic cell line ATDC5. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Western Blot Analysis Cell Line: Human primary lymphatic endothelial cell (LEC)s; ATDC5 chondrogenic cells Concentration: 10 μM Incubation Time: 0, 5, 10, 30, 45, 60 min Result: Inhibited FGFR3 phosphorylation at Tyr 724 in human primary lymphatic endothelial cell (LEC)s. Inhibited the FGF2-mediated ERK/MAPK phosphorylation in FGFR3-expressing chondrocytic cell line ATDC5. Cell Proliferation AssayCell Line: Human primary lymphatic endothelial cell (LEC)s Concentration: 2.5 μM, 5 μM, and 10 μM Incubation Time: 15 min for pre-incubation and co-incubation with 1 μM 9-cisRA for 48 hr Result: Inhibited LEC proliferation. Cell Migration AssayCell Line: Human primary lymphatic endothelial cell (LEC)s Concentration: 5 μM Incubation Time: 15 min for pre-incubation and co-incubation with 1 μM 9-cisRA for 24 hr; observed at 0, 24, 48 hr Result: Inhibited LEC migration tubule formation. In Vivo:VSPPLTLGQLLS (1 mM; intranasal dropping; onced daily for 7 d) blocks 9-cisRA-induced lymphangiogenesis in vivo, while 9-cisRA is an isoform of vitamin A involving in AIDS-related Kaposi Sarcoma. VSPPLTLGQLLS alleviates the bone growth retardation in bone rudiments from mice mimicking human thanatophoric dysplasia type II (TDII), reversed the neonatal lethality of TDII mice. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Animal Model: Lymphatic reporter mice, Prox1-GFP model [1] Dosage: 1 mM Administration: Intranasal dropping; once daily for 7 days; accompanied with 1 mM 9-cisRA or not Result: Significantly inhibited total lymphatic vessel length and number of sprouts compared increase induced by 9-cisRA. Animal Model: Fgfr3 Neo-K644E/+ EIIa-Cre mice (TDII mice) from Fgfr3 Neo-K644E/+ mice crossed with heterozygous EIIa-Cre mice Dosage: 10 μM Administration: Treated for 7 days Result: Suppressed FGFR3-mediated growth inhibition in cultured murine metatarsal bones. Rescued the lethal phenotype in thanatophoric dysplasia type II (TDII) mice. Rescued the abnormal growth plate and the lung phenotypes in the TDII mice.