SKP2 and neoplasm: Our results here may unveil the puzzle that loss of PCBP1 destabilizes p27 mRNA at the first step to lead to low p27 expression, irrespective of Skp2 levels and the posttranslational regulation via other manners (Fig. 5c, d), since Skp2 expression is rarely seen to be upregulated in the detected tumor samples (Fig. 6; Additional file 11: Figure S9C).