Isolation of stable MKRN1 transfectants. (a) Protein expression levels of MKRN1, His-tagged proteins, ubiquitinated proteins and β-actin in MKRN1 transfectants, Fmkrn-24 and 21, and the parental ras-NIH3T3 cells were examined by Western blotting using the anti-MKRN1 peptide antibody, the anti-His antibody (lower panel), the anti-ubiquitin antibody or the anti-β-actin antibody. (b) Expression of MKRN1 mRNA in MKRN1 transfectant Fmkrn-24 and ras-NIH3T3 cells was examined by RT-PCR. MKRN1 sequence between nucleotide positions 29 and 536 was amplified. The position of PCR products is indicated by an arrow. (c) Phase morphology of ras-NIH3T3 and Fmkrn-24 cells. Original magnification, ×100.