RBP1 and polycystic ovary syndrome: To further validate the differentially expressed PCOS proteins identified from DIGE, the expression levels of ANXA 6, TPM2, HSP90B1, CALM1, RBP1, and PGRMC1 in ovary tissues of PCOS patients (n = 10) and controls (n = 10) were compared using WB and IHC.