STEAP4 and keratoconus: The altered protein expression in all 4 KC samples underscored cytoskeletal regulation, such as the increased microtubule protein HN1, vesicle transporter USO1 and LTOR5 as well as calcium binding RCN1, and the downregulated voltage channel VDAC1 on cell membrane and cell survival-associated STEAP4 (mitochondrial), ADH7 (defence against oxidative stress), BZW1 (histone H4 regulation), PHGDH (electron transfer in ATP synthesis) and calcium responsive OLA1 (Supplemental Table S7).