Genetically engineered tissue culture of the Madagascar Periwinkle (Catharanthus roseus Vinca rosea), produced as a source of the dim alkaloids vinblastine (VLB) and vincristine (VCR), used as chemotherapy agents in the treatment of certain cancers, notably acute lymphoblastic leukaemia, Hodgkin's disease & non-Hodgkin lymphomas. VCR and VLB are always used in conjunction with other drugs. Both alkaloids are believed to interfere in the process of mitosis (cell division) by damaging the mitotic spindle, the apparatus of cell division. Both compounds have a short-lived toxicity; VCR towards the nervous system and VLB to the bone marrow.