YBX1 and cancer: For example, ribosomal S6 kinase 2 (RSK2) mediated phosphorylation of YB-1 at the Ser102 site promotes the formation of the YB-1/KLF5 transcription complex, which jointly regulates the expression of BLBC-specific genes such as keratin 16 (KRT16) and lymphocyte antigen 6 family member D (Ly6D), promoting cancer cell proliferation (40) (Figure 3).