Implication of the FER and CRKL kinases in S-phase replication of HeLa and HuH7 cells. Cells were transfected with FER, CRKL or control siRNAs and analyzed 72 h post-transfection. (A, B), western blot analysis of FER and CRKL expression in HeLa (A) and HuH7 (B). (C), Representative fluorescence microcopy images from HeLa cells (EDU labeling). (D, E), Cell proliferation assay. EDU or methyl-Thymidine incorporations were performed 72 h (a) and 96 h (b) after transfections of HeLa (D) and HuH7 (E) cells. Replication is expressed as the proliferation index (EDU for HeLa cells) and cpm/μg of protein (methyl-3H-Thymidine for HuH7). The statistical significance was (P < 0.05) and (P < 0.001) in HeLa and HuH7 cells, respectively, relative to the control siRNA.