No not really, though technically, the bull breeds do descend from mastiffs.
hi blacktimberwolf your knowledge of dogs is excellent!! here is what i have read about the bull breeds coming from mastiffs
British Chief Caractacus was defeated by Emperor Claudius of the Roman
Empire in 50 AD. The Romans were so impressed by the fierce fighting
dogs they met when they landed in Britain that they began importing the
dogs back to Rome for use in the great arena, alongside the other dogs
they already possessed for such uses. It seems reasonable to assume
that the British dogs were at some points crossed into the Roman dogs.
Ancestors of these dogs were exported to all parts of the continent,
including France and to Spain where they became renowned fighting
dogs. Later some of these dogs found their way back to Britain. A variety
of breeds of mastiff and bulldog-type were scattered about, and most
likely contributed to the creation of the bulldog that was to be one of the
main ingredients used in the development of the Pit Bull.