I noticed they're are no sources for any of this.
Matthew (the tax collector)
was an apostle and an eyewitness to the life of Christ. Why would an eyewitness need to base his gospel on someone (Mark) who was not an eyewitness.
Luke (The physician) was a traveling companion of Paul. Paul met with Peter and some of the other disciples for 15 days (Galations 1;18). I have a feeling Paul and Peter did not talk chariot races in those 2 weeks.
John was also an apostle and an eyewitness. Once again why would an apostle and an eyewitness need to use the gospel of a non eye witness.
And if these 2 eyewitnesses did copy anything from Mark, it was probably because it was the truth. After all Mark was a companion of Peter (essentially the main apostle). I go into Peter in greater detail in this thread:
http://www.internationalskeptics.com/forums/showthread.php?t=85633&highlight=peter
And did these 11 apostles choose to die for what they knew to be a false story.
Apostolic Age—1st century
* Saint Stephen, Protomartyr, was stoned c. 35 A.D.
* James the Great (Son of Zebedee) was beheaded in 44 A.D.
* Philip the Apostle was crucified in 54 A.D.
* Matthew the Evangelist killed by a halberd in 60 A.D.
* James the Just, beaten to death by a club after being crucified and stoned.
* Matthias was stoned and beheaded.
* Saint Andrew, St. Peter's brother, was crucified.
* Mark was beaten to death.
* Saint Peter, crucified upside-down.
* Apostle Paul, beheaded in Rome.
* Saint Jude was crucified.
* Saint Bartholomew was crucified.
* Thomas the Apostle was killed by a spear.
* Luke the Evangelist was hanged.
* Simon the Zealot was crucified in 74 A.D.
(Note: John the Evangelist according to legend was cooked in boiling hot oil but survived. He was the only one of the original twelve Apostles who was not martyred).
http://en.wikipedia.org/wiki/Christian_martyrs