To investigate the effect of NNMT knockdown on breast cancer cells growth in vivo, Bcap-37 cells infected with NNMT shRNAs (NNMT shRNA 1# and NNMT shRNA 2#) and shRNA NC were subcutaneously injected into the upper portion of the right hind limb of 6 BALB/c nude mice for each group separately. The gene discussed is NNMT; the disease is breast carcinoma.