Moreover, TSC01682 treatment in osteosarcoma cells also caused a decrease of other CRL4B components including CUL4-associated factor 11 (DCAF11) and DCAF13, but an increase of two CRL4B substrates including cyclin-dependent kinase inhibitor 1A (CDKN1A, also known as p21) and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) through inhibiting their ubiquitination.
Knocking down any component of the CRL4B<sup>DCAF11</sup> complex, including CUL4B, DDB1 or DCAF11, using short hairpin RNAs (shRNAs) attenuated the ubiquitination level of p21<sup>Cip1</sup>, inhibited osteosarcoma cell proliferation, led to cell cycle arrest at S phase, and decreased colony formation rate.