I have been on a rotation project in the lab of Dr. D. Nathans, who has received the Nobel Prize in 1978 for his work on restriction enzymes. Though I have spent only two month in his lab, I believe it was my richest scientific experience that had the most profound influence on the development of my scientific views.
        The project involved in vivo labeling of NIH3T3 cells with P32 and immunoprecipitation of JunB protein with polyclonal antibodies.  I demonstrated that JunB is phosphorylated on Ser and Thr by doing phosphoaminoacid analysis.  I purified radioactively labeled JunB by SDS PAGE and cleaved the eluted protein with CnBr.  To find which peptide contained radioactive label I used four antibodies raised against different parts of JunB protein.  The radioactive JunB peptide found by this approach contained phosphorylation sites similar to c-Jun protein, which is a JunB homolog.
        Since I have obtained promising results during my first rotation in Jeff Corden’s lab and because I was interested more in the understanding of the CTD function, I left Nathan’s lab to continue my work on the C-terminal domain of RNA polymerase II.