Expression of miR-339-5p in breast cancer cells and tissues. A. miRNA microarray and real-time PCR analysis of miR-339-5p expression. MDA-MB-231 and MCF-7 cells were grown in monolayer for 5 days, and total RNA was extracted from the cells and subjected to microarray and real-time PCR analyses. B. Real-time PCR analysis of miR-339-5p expression. Fresh tissue samples from breast cancer patients with or without lymph node metastasis and from patients with benign breast diseases were obtained from the surgery room. Total RNA was extracted from the tissues and subjected to real-time PCR analysis.