BIRC5 and chondrosarcoma: G2/M phase cell-cycle arrest has been described by Lechler et al.25 in two chondrosarcoma cell lines after siRNA knock down of survivin; however, Yang et al.26 showed a decrease in S phase after knock down of survivin in the same cells.26 We found an increase in S phase after treatment with YM155 in two of our chondrosarcoma cell lines and an increase in G2/M phase in JJ012 cells after BIRC5 knock down.