Motif analyses revealed kinases with likely involvement in osteoblastogenesis. (A) Significantly overrepresented linear phosphorylation motifs were identified with Motif X and matched to kinases predicted with NetworKIN (Linding et al. 2008), in which an increase in purple intensity equals an increase in the percentage of the given site that is predicted to be phosphorylatable by the given kinase (left). The identified motifs were hierarchically clustered according to the average phosphorylation dynamics of the sites matching each motif. The average change in phosphorylation of sites matching the motif in each time point is color-coded blue for decreased or red for increased compared to undifferentiated cells. Only average phosphorylation changes with a mean significantly different from zero on confidence level 0.01 were included. (B) Class I sites were clustered according to their temporal dynamics (left). Fisher's exact test with Benjamini–Hochberg adjustment was used to identify kinases with significant overrepresentation of substrates within any of the clusters (right).