C4BPA and cervical cancer: In addition, the 37 genes included six members of the small proline-rich protein gene family: SPRR1A, SPRR1B, SPRR2A, SPRR2D, SPRR2E, and SPRR3. Previous studies have revealed that many small proline-rich protein genes were downregulated in cervical cancer relative to normal cervical tissue (43, 44), suggesting their tumor suppressor roles.