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6 p.-6 fig., Understanding the physical and biological effects of the absence of gravity is necessary to conduct operations on space environments. It has been previously shown that the microgravity environment induces the dissociation of cell proliferation from cell growth in young seedling root meristems, but this source material is limited to few cells in each row of meristematic layers. Plant cell cultures, composed by a large and homogeneous population of proliferating cells, are an ideal model to study the effects of altered gravity on cellular mechanisms regulating cell proliferation and associated cell growth. Cell suspension cultures of Arabidopsis thaliana cell line (MM2d) were exposed to 2D-clinorotation in a pipette clinostat for 3.5 or 14 h, respectively, and were then processed either by quick freezing, to be used in flow cytometry, or by chemical fixation, for microscopy techniques. After long-term clinorotation, the proportion of cells in G1 phase was increased and the nucleolus area, as revealed by immunofluorescence staining with anti-nucleolin, was decreased. Despite the compatibility of these results with those obtained in real microgravity on seedling meristems, we provide a technical discussion in the context of clinorotation and proper 1g controls with respect to suspension cultures. Standard 1g procedure of sustaining the cell suspension is achieved by continuously shaking. Thus, we compare the mechanical forces acting on cells in clinorotated samples, in a control static sample and in the standard 1g conditions of suspension cultures in order to define the conditions of a complete and reliable experiment in simulated microgravity with corresponding 1g controls., This work was supported by grants of the Spanish National Plan for Research and Development, Ref. Nos. AYA2010-11834-E, and AYA2012-33982 and by European Space Agency (ESA) Access to GBFs contract numbers 4200022650 & 4000105761. KYK was sup-ported by the Spanish Consejo Superior de Investigaciones Científicas (CSIC) JAE-PreDoc Program (Ref. JAEPre_2010_01894)