KLF4 and obstructive sleep apnea syndrome: PPI analysis showed that FOS, IL6, ATF3, JUN, DUSP1, EGR1, PTGS2, FOSB, CXCL2, NR4A1, SOCS3, ZFP36, NR4A2, KLF4, AREG, and CD69 interacted with each other (Figure 2B), with FOS and IL6 probable hub nodes, followed by ATF3 and JUN, since they had the most interactions with hypoxia-related genes involved in OSA (Figure 2C).