Improved methods and devices for performing an endoscopic surgery including a system for performing minimally invasive procedures including a flexible catheter having a working space expanding system positioned at a distal portion, the working space expanding system movable from a non-expanded insertion position to an expanded position forming an expanded region to expand the working space within the body lumen. A tissue retractor having an inner member positioned within an outer guide member has a plurality of closed loops at a distal portion forming a petal-like structure. The loops are positioned in a collapsed position within the outer guide member and are movable to an expanded position when exposed from the outer guide member.