RUNX2 and ocular melanoma: Moreover, in cells incubated in OM, the gene expression of Runx2, a key transcription factor driving osteogenesis of MSCs, and of collagen type 1 alpha-1 (Col1A1), and tissue non-specific alkaline phosphatase (TNAP), did not vary significantly as differentiation progressed (Fig. 1A,D,H).