Difficulties understanding a pathway
So if you're reading the flowchart, understanding the notation of the arrows is important:


We have rectangles around the gene products
There's a circle, denoted by DNA, noting that the proteins are expressing the product that follows through interaction with DNA
The solid line with an arrowhead means there's some sort of interaction
The solid line with the blunted or T head means this pathway or interaction has been abrogated somehow
The solid line with the slash through it means there's some missing interaction that we don't see
The +p means phosphorylation
The double solid line to the left is the plasma membrane, whereas the dotted line central to the figure is the nuclear envelope
The dotted line means an indirect effect


Source: http://www.genome.jp/kegg/document/help_pathway.html

The pathway is kind of broad but it provides some mechanisms for tumorigenesis from two standpoints: chromosomal instability, and microsatellite instability. The pathways we're seeing promotes the tumor development by upregulating proliferation signals, and downregulating apoptosis pathways. There's bound to be more to it, especially since we see other players involved when we get into cases like metastasis like snail1/2, Met, Src, etc. Below is a survey of apoptotic pathways from Nature, with pro-apoptotic in red, and pro-survival in green:


Source: http://www.nature.com/reviews/poster/apoptosis/index.html

Ignoring the therapeutic targeting jargon, you can see that when growth factors bind, the cell generally pushes towards a survival state. When death factors bind or something goes wrong, the cell pushes toward an apoptotic state. Cancers, however, are intrinsically disregulated:



They have methods of overstepping their boundaries as cells, which is what makes them problematic. The general conclusion I'd draw from that KEGG pathway, though, is that many pathways need to be disregulated to end up with colorectal tumors, and the method of disregulation is (a) downmodulated mismatch repair, and (b) chromosomal aberrations due to duplication, etc. Andkeeping in mind the box of oncogenes vs tumor suppressors in the corner: "An important difference between oncogenes and tumor suppressor genes is that oncogenes result
from the activation (turning on) of proto-oncogenes, but tumor suppressor genes cause cancer when they are inactivated (turned off)"