Table 1. Key statistics of phage library selection experiments.

	A8	A9	A10	A12	A15	A17	A19
Phage enrichment in the first round of library screening	3000	>10,000	50	200	10,000	5	500
Number of customized reduction libraries prepared and screened	5	4	0	3	6	0	4
Total number of SH3 clones identified by sequencing	332	142	190	384	172	47	203
Total number of selected SH3 domains	8	7	0	8	14	0	14