There are cell signaling pathways and they are Erb pathway, VEGF pathway, PARP pathway, IGF-1 pathway, Hedgehog (Hh) pathway, and Ubiquitin-Proteosome pathway.

Erb pathway

There are four types of Erb receptors including EGFr (ErbB1), HER2/neu (ErbB2), HER3 (ErbB3), and HER4 (ErbB4). Ligands of these receptors bind to Erb receptors, then dimerization happens, finally the tyrosine kinase of receptors are activated, which results in first increased tumor proliferation, angiogenesis, growth, and metastases potential; and second decreased apoptosis.

VEGF pathway

VEGF family includes VEGFR-1, VEGFR-2, and VEGFR-3. VEGF pathway is activated and cell signal is transmitted, as a results increased angiogenesis, lymphangiogenesis happens.

PARP pathway

PARP is involved in the DNA repair after DNA damage due to radiation therapy, chemotherapy and so on. PARP inhibitors can prevent the DNA repair after DNA damage, which results in persistent DNA damage and finally the apoptosis 0r cancer cell death.

IGF-1 pathway

IGF-1 pathway provides a potent proliferative signaling that stimulates growth in many different cell types and blocks apoptosis including cancer cells.

Hedgehog (Hh) pathway

Hh pathway is relative to cell proliferation, survival, and angiogenesis.

Ubiquitin-Proteosome pathway

This path is involved in the ubiquitination and proteasomal degradation of CRL substrates, which is important for normal cell cycle regulation and DNA replication related to cancer cell growth.