Table 1. IC₅₀ values (μM) of kinase inhibition, A431 cytotoxicity assay and EC₅₀ (μM) against P13K.

Compd #	EGFR Kinase Inhibition	VEGFR-2 (Flk-1) Kinase Inhibition	VEGFR-1 (Flt-1) kinase Inhibition	PDGFR-β Kinase Inhibition	A431 Cytotoxicity	PI3K Activity	Flt-3 Activity
1	15.07 ± 3.1	22.6 ± 4.5	118.1 ± 19.4	2.8 ± 0.42	49.2 ± 4.7	21.6	41.2 ± 5.7
2	10.41 ± 1.2	56.3 ± 7.1	160.1 ± 28.9	40.3 ± 5.1	14.1 ± 2.0	12.2	39.6 ± 4.1
13	0.23 ± 0.05
Semaxinib		12.9 ± 2.9
14			14.1 ± 2.8
DMBI				3.75 ± 0.31
Cisplatin					10.6 ± 3.5
15						1.5
16							2.9 ± 0.031

In-cell kinase activity was assessed by a “cytoblot” developed in our laboratory using A431 cells which overexpress EGFR, SF539 cells for PDGFRβ, U251 cells for VEGFR2, A498 cells for VEGFR1, MV 3:11 cells for Flt-3, and HeLa cells for PI3K as described in the detailed methods section.