The present invention relates to a novel cell line isolated from a rat osteosarcoma cell line has the following characteristics: a) a non- expressed p53 protein; b) a normal RB-1 gene; c) a 1O× amplified c- myc gene; d) a normal c-fos gene; e) a deregulated immediate early gene response; f) a canalicular network MATRIGEL™ growth pattern; g) tumorigenic in congenitally athymic mice; h) no alkaline phosphatase activity; i) an ability to produce one or more of the following growth factors: 1) an osteoblastic differentiation growth factor, 2) a non- heparin binding mitogenic growth factor, 3) a first heparin binding mitogenic growth factor, 4) a second heparin binding mitogenic growth factor, and 5) a third heparin binding mitogenic growth factor; and an ability to be serially propagated greater than sixty population doublings. PPThe present invention also relates to growth factors having the characteristics of growth factors isolated from the rat osteosarcoma cell line.PPThe present invention further relates to a process for producing such growth factors.
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