A human gene termed CIF130 and its expression products can alter the spatial or temporal patterns of mitosis or cell cycle progression of a human cell. The beam splitting means are capable of diving up a light beam that is incident on the beam shaping unit into two partial beams. It includes a guide device with surfaces of two pole pieces each attracted by a magneticelectrostatic field transmitted by one of the ends, or generating a magneticelectrostatic field attracting one of the ends, the magneticelectrostatic forces exerted on the two ends are of different intensity, in order to attract only one end into contact with only one of the pole piece surfaces.