SERPINB4 and cancer: Several reports indicate that serpinB4, corresponding to the acidic isoform, is the main circulating isoform in patients with epithelial cancers [40], [41], [26] and an elevated serpinB4/serpinB3 mRNA ratio, detectable in different cancer cells [22], [23], [42], has been described as a poor prognostic factor for early-stage cervical cancer.