RACGAP1P1 and cancer: Importantly, the cancer cell proliferation and migration promotion effects were abrogated in DICER1-knock out HCC cells (Fig. 5a–d, Supplementary Fig. 1b), supporting the notion that the 3’UTR of RACGAP1P requires mature miRNAs for its function towards RACGAP1. Taken together, our results demonstrate that RACGAP1P, operating as a ceRNA, activates RACGAP1/RhoA/ERK pathway to favour malignant phenotypes of HCC (Fig. 5e).