Table 1.

Results of ELISA Plk1 PBD Competition Assays^a

Entry	Compd.	IC50 (μM)
1	PLHST	NA
2	1	9
3	2a	0.003
4	2a†b	0.003
5	3b	0.005
6	3c	0.001
7	3c(S/A)	0.8
8	3d	0.001
9	3e	0.001
10	3f	0.004
11	3g	0.005
12	3h	0.006
13	3i	0.04
14	3j	0.003
15	3k	0.002
16	3l	0.001
17	3m	0.001
18	3m(S/A)	0.15
19	3n	0.015

^aDetermined by ELISA competition assays as described. Binding curves are shown in Figures S3.

^bAs defined in the text, 2a^† is a variant of 2a, in which the pThr residue is replaced by a (2S,3R)-2-amino-3-methyl-4-phosphonobutyric amide residue⁴⁴ and an N-terminal PEG group has been appended to increase water solubility.³⁰