CREB1 and Azoospermia: In contrast, among patients with cryptorchidism and abrogated mini-puberty, who are at high risk of developing azoospermia, we observed a weak increase in CREB1 and ATF2 (CREB2) expression levels, compared to the low infertility risk group (LIR), and the CREB3 and CREB5 expression levels remained unaltered (Table 1).