KL and breast cancer: To investigate the amino acid sequence preference for Kla in BC cells, Kla Motif analysis of the peptide sequences (10 amino acids) upstream and downstream surrounding the identified Kla sites was performed using Motif-X, and results revealed that the Kla sites preferably located downstream of glycine, lysine, proline, or serine residues and upstream of lysine or isoleucine (Fig. 6B-C).