The c‐myb proto‐oncogene product (c‐Myb) induces transcription of a group of target genes involved in the G1/S transition and in anti‐apoptosis. The level of c‐Myb is negatively regulated by the Wnt signal, but it remains obscure how c‐Myb activity is positively regulated. We have found that ribosomal protein L4 (RPL4) binds to the DNA‐binding domain of c‐Myb. Co‐immunoprecipitation experiments also indicated that RPL4 interacts with c‐Myb. When c‐Myb was overexpressed in CV‐1 cells, significant amounts of RPL4 moved to the nucleoplasm from the nucleolus. RPL4 stimulated the c‐Myb‐dependent expression of a c‐myc‐luciferase reporter construct. Chromatin immunoprecipitation assays indicated that RPL4 binds to the 5′‐regulatory region of the c‐myc gene via c‐Myb. Serum starvation and 2‐deoxyglucose treatment of NIH3T3 cells induced the movement of RPL4 from the nucleoplasm to the nucleolus. Furthermore, c‐myc mRNA levels were reduced by either serum starvation or 2‐deoxyglucose treatment, and the degree of reduction in the c‐myc mRNA level was correlated with the RPL4 level. These results suggest that growth factor and nutritional signals positively regulate c‐Myb activity via its interaction with RPL4. Thus, RPL4 plays an important role in c‐myc expression by interacting with c‐Myb in response to growth factor and nutritional signals.