CCND1 and pachyonychia congenita: These results show that MCM2, MCM3, MCM4, MCM5, MCM6, MCM7, CCND1, and CCNE1 are targets of E2F1 gene in PC cells, and the RPL21 regulates E2F1 binding to the above target genes promoter through the control of E2F1 transcription.