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Antibodies raised in rabbits against a mouse plasma cell tumor were labeled with 131 I and injected along with normal rabbit globulin labeled with 125 I into plasmacytoma bearing mice and the degree of localization of the antibodies in the tumors determined. There was localization of the anti-tumor antibody above the background localization of the normal globulins. The localization apparently took place largely on the tumor cell surfaces since following cell fractionation experiments the fixation was found to be largely in the microsome fraction. The antibodies raised against the tumor also showed localization in liver, spleen and brain.

International audience; There is evidence for both transcriptional and post-transcriptional levels of regulation of c-fos and c-myc proto-oncogenes. Transcription of both genes can be regulated at the level of initiation. However, it was recently shown in various situations for c-myc, and in one case for c-fos, that these genes can also be down-regulated by a block to elongation of nascent RNA chains. Both c-myc and c-fos mRNAs are known to be extremely unstable (half-lives around 10-15 min) and c-myc RNA turnover has been shown to be modulated under various physiological situations. Atypical c-myc RNAs found in certain mouse plasma cell tumors (MPCs) and Burkitt, lymphomas (BLs) are significantly and sometimes dramatically more stable than their normal counterparts. In this review we report that: i) transcriptional control elements reside in murine c-myc and c-fos first exons. Daudi cells provide an example of c-myc activation via removal of this block to elongation; ii) elements necessary for the rapid degradation of c-fos and c-myc RNAs reside in their 3' non-coding regions; iii) these destabilizing elements can be counteracted by atypical 5' sequences found in abnormal c-myc transcripts from BLs and mouse plasmocytomas.