Abstract: Here is disclosed a cell culture tank comprising a cylindrical screen mounted upright within the cell culture tank and having upper and lower openings through which culture medium flows, a pipe for supply of oxygen or oxygen containing gas and an agitator adapted to produce a flow of the culture medium, both the pipe and the agitator being provided within the cylindrical screen, wherein the agitator drives the culture medium to flow downward through the lower opening of the cylindrical screen, then to flow upward into a space defined between the cylindrical screen and the inner wall of the cell culture tank, and a relationship between an ascending velocity of the culture medium and a sinking velocity of the adherent carriers produces in the space between the cylindrical screen and the inner wall of the cell culture tank a floating region within which the adherent carriers float in the culture medium and a separating region within which the adherent carriers are separated from the culture medium.

Abstract: Disclosed herein is a process for producing erythropoietin, comprising bringing a material containing erythropoietin into contact with an adsorbent having a monoclonal anti-erythropoietin antibody, adsorbing erythropoietin on the adsorbent, and eluting the absorbed erythropoietin from the adsorbent.