HHLA2 and nonpapillary renal cell carcinoma: Then, we further assessed the migration ability of the ccRCC cell lines after knockdown HHLA2 expression in the LV-HHLA2-sh1 as well as LV-HHLA2-sh2 group in contrast to the LV-NC group, and as shown in Fig. 3d–f, at the time point of 48 h, the relative distance of LV-HHLA2-sh1 (P < 0.0001 in 786-O cells, and P < 0.0001 in ACHN cells) as well as LV-HHLA2-sh2 (P < 0.0001 in 786-O cells, and P < 0.0001 in ACHN cells) group was significantly increased in contrast to the LV-NC group, suggesting that knockdown of HHLA2 expression significantly reduce the migration ability of ccRCC cell lines.