AFP is a protein that in humans is encoded by the AFP gene The AFP gene is located on the q arm of chromosome 4 (4q25). Maternal AFP serum level is used to screen for Down syndrome, neural tube defects, and other chromosomal abnormalities.

CEA describes a set of highly related glycoproteins involved in cell adhesion. CEA is usually present at very low levels in the blood of healthy adults (about 2-4 ng/mL). it can be used as a tumor marker in clinical tests.

PSA is present in small quantities in the serum of men with healthy prostates, it is often elevated in the presence of prostate cancer or other prostate disorders.

CA-125  is a protein that in humans is encoded by the MUC16 gene.MUC16 is a member of the mucin family glycoproteins.CA-125 has found application as a tumor marker or biomarker that may be elevated in the blood of some patients with specific types of cancers,[6] or other conditions that are benign.

CA19-9 is a tetrasaccharide which is usually attached to O-glycans on the surface of cells. It is known to play a vital role in cell-to-cell recognition processes. It is also a tumor marker used primarily in the management of pancreatic cancer.

HE4 is an important clinical biomarker used for the detection of epithelial ovarian cancer (EOC). 

Ferritin is a universal intracellular protein that stores iron and releases it in a controlled fashion. The protein is produced by almost all living organisms. In humans, it acts as a buffer against iron deficiency and iron overload.Ferritin is found in most tissues as a cytosolic protein, but small amounts are secreted into the serum where it functions as an iron carrier. Plasma ferritin is also an indirect marker of the total amount of iron stored in the body; hence, serum ferritin is used as a diagnostic test for iron-deficiency anemia.

PGI is the pro-form of pepsin. It is produced in the stomach and secreted into the gastric lumen, but a small amount is also released into the blood. Alterations in the serum pepsinogen concentration may indicate gastric abnormalities.

PGII is the pro-form of pepsin. It is produced in the stomach and secreted into the gastric lumen, but a small amount is also released into the blood. Alterations in the serum pepsinogen concentration may indicate gastric abnormalities.

NSE is an enzyme that in humans is encoded by the ENO2 gene. It has been used as a typical tumor marker and shows a potential to diagnose malignant pleural effusion.