KLF2 and osteoporosis: Notably, we have recently observed that another class of mevalonate-inhibiting drugs, the nitrogen-containing (N-) bisphosphonates (N-BP), which are used for the treatment of osteoporosis, can also trigger ERK5 phosphorylation and KLF2 and KLF4 induction in various cells, including ECs and differentiated primary human osteoblasts [73].