The debate on the cell of origin of human retinoblastoma lasted for more than one century. In the recent issue of ldquo;cellrdquo;, David Cobrinikprime;s group shows that L/M cone precursors are the most likely answer as they have an intrinsic circuitry, including murine double minute 2 (MDM2), Nmyc, the nuclear receptors retinoid X receptor and thyroxine receptor 2, making them extremely sensitive to transformation following retinoblastoma gene inactivation.
Despite its low incidence, retinoblastoma and its rela ted gene (Rb gene) have attracted some of the most brilliant minds in medicine and biology fi elds over the past years. Great advances have been achieved in the tumoregenesis mechanism and clinical management of retinoblastoma recently. However as always , more questions arise from those results. In order to improve retinoblastoma re search in China, we need to strengthen the communication and cooperation with di ffe rent countries, different institutes and disciplines, and utilize the great reso urces of retinoblastoma patients in China.
With the method of PCR-SSCP combined sequencing,we analysed the mutations in the RB1 gene of 10 retinoblastoma samples. All 27 exons of RB1 gene have been examined. The PCR products were digested with some restriction endonuclease to the size of about 200 bp and then denatured into single strands. Loading the single strands of DNA into the 6% polyacrilamide gel,we followed the technology named SSCP to f/nd the abnormal bands in the SSCP gel. After that, the samples found with the abnormal bands in the SSCP gel were amplified again and sequenced to confirm the types and locations of the mutations in the RB1 gene. We have fonnd some kinds of mutations in the RB1 gene. （Chin J Ocul Fundus Dis,1994,10:17-20）
The Chinese human hepatocellular carcinoma cell SMMC7721 has been analysed by flow cytometry, Southern blotting and Western blotting. The results indicated that SMMC7721 cell is a hypoploid cell with a 0.81 DNA index, and that SMMC7721 cell has internal deletion in the 5'-end of its Rb gene and has no Rb gene product (Rb protein). The normal Rb cDNA has been inserted into a retrovirus vector DOL and introduced into SMMC7721 cells by electrporation transfection technique.About 75% of transfected SMMC7721 cells have been killed by Rb gene product. The remain 25% cells are alive as exogenous Rb gene has been mutationally inactivated. （Chin J Ocul Fundus Dis,1994,10:21-24）