A surgical stapling instrument including an actuator (4043) configured to be retracted relative to the distal end of a "disposable loading unit" (4016) comprising a staple cartridge assembly (4018) and an anvil assembly (4020) and rotate the anvil assembly between an open position and a closed position. The actuator can include a cam (4053), where the cam can include an arcuate profile having an apex (4055) configured to be in contact with the anvil assembly when the anvil assembly is in a closed position. In at least one such embodiment, the anvil assembly and cartridge assembly can apply a clamping force to the soft tissue prior to the staples being deployed to prevent, or at least inhibit, soft tissue from flowing, or 'milking', out of the distal end of the disposable loading unit. In various embodiments, a surgical stapling instrument can include a disposable loading unit having an anvil assembly which can be moved between open, closed, and/or collapsed positions to facilitate the insertion of the disposable loading unit through a trocar.
