| 摘要 |
The present invention relates to a novel cell line isolated from a rat osteosarcoma wherein the cell line has the following characteristics: a) a mutated p53 system, b) a normal RB-1 gene as compared to a non-tumorigenic Sprague-Dawley rat cell control, c) a normal c-myc gene as compared to a non-tumorigenic Sprague-Dawley rat cell control, d) a normal c-fos gene as compared to a non-tumorigenic Sprague-Dawley rat cell control, e) a deregulated immediate early gene response, f) a canalicular network MATRIGEL(Trademark), growth pattern, g) tumorigenic in nude mouse, h) no alkaline phosphatase activity, i) an ability to produce one or more growth factors selected from the group consisting of: 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 j) an ability to be serially propagated greater than sixty population doublings. The present invention also relates to growth factors having the characteristics of growth factors isolated from the rat osteosarcoma cell line. The present invention also relates to a process for producing a growth factor comprising: a) growing an osteosarcoma cell line in a culture medium, and b) recovering the growth factor from the medium. The present invention also relates to a process for producing a growth factor comprising: a) isolating mRNA from an osteosarcoma cell line which codes for the growth factor, b) making cDNA of the mRNA, c) expressing the cDNA in an expression vector; and d) recovering the growth factor.
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