To test whether SPIDER can validate PSMI in a cell lysate, we examined the interaction between Rapamycin and FK-binding protein 12 (FKBP12) to test whether SPIDER can validate protein-small molecule interaction in total cell lysate.We performed SPIDER assay by incubating biotin-Rapamycin or biotin control with the total lysate of FKBP12-overexpressed HEK293T cells