Figure 1.

A, Among 51 ABC transporters, ABCB1 is a representative transporter that enhances outward efflux activity of anticancer drugs from the inside to the outside of cancer cells, resulting in acquired multidrug resistance. Enhanced transcriptional activation of ABCB1, either by chronic exposure to anticancer drugs or by acquired multidrug resistance, is mediated through the environmental stimuli‐naïve Y‐box binding protein‐1 (YBX1). B, YBX1‐induced activation of ABCB1 is first presented as a transcriptional mechanism of how tumor multidrug resistance is acquired during chemotherapeutic treatments in various human malignancies. YBX1 also induces activation of various other resistance‐related genes, including MVP/LRP,TOP2A,CD44,CD49f,BCL2,MYC, and androgen receptor (AR). C, Structure and phosphorylation sites of the YBX1 protein. Phosphorylation at Ser102 in the cold shock domain is essential for nuclear translocation and oncogenic activation of YBX1. B/A repeat, basic and acidic amino acid repeat sequences