So when both of these genes in the allele pair and coding for a specific type of phosphatase that inactivates some specific type of molecule in this process are actually knocked out or destroyed, that may lead to tumor formation because the cell will not be able to correctly terminate that process by using these phosphatases. So we know how abnormality can lead to cancer here as well as here. What about this final case? So we said that we could actually terminate the pathway by inactivating that receptor protein. In this case, it's the EGF receptor. Now, in some cases we see that over expression of these tyrosine kinase domains.