  MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression
post-transcriptionally. They are involved in key biological processes and then
may play a major role in the development of human diseases including cancer, in
particular their involvement in breast cancer metastasis has been confirmed.
Recently, the authors of ref.(\cite{key1} have found that miR-429 may have a
role in the inhibition of breast cancer metastasis and have identified its
target gene CRKL as a potential candidate. In this paper, by using systems
biology tools we have shown that CRKL is involved in positive regulation of
ERK1/2 signaling pathway and contribute to the regulation of LYN through a
topological generalization of feed forward loop.
