MMP2 and cancer: Herein, the MCF-7 and HaCat cell lines were selected as MMP-2-negative and MMP-2-positive, respectively, which was confirmed by the reverse transcription polymerase chain reaction (RT-PCR) analysis of MMP-2 mRNA levels from various human cancer cell lines including A549, MCF-7, HeLa, AGS, HaCat, HCT15, and 293A (Supplementary Figure S1).