Knockdown of KIFC1 expression induced G2/M phase arrest, upregulates expression of p21 and suppresses activation of cdc2 in A549 and SPC-A1. The letters (A,B) (C,D) and (E,F) represent the result of FCM, statistical views and Western blotting analysis, the letters (A,C,E) and (B,D,F) represent A549 and SPC-A1 cell lines, respectively. *, P<0.05; **, P<0.01; ***, P<0.001. KIFC1, kinesin family member C1; p21, cyclin-dependent kinase inhibitor 1A; cdc2, cell division cycle protein 2 homolog.