The work by Cristobal et al (2014) is an interesting study that builds on our and other recent work implicating downregulation of miR-133b in CRC and correlate with CRC metastasis (Lin et al, 2014). To further confirm the role of miR-133b in the metastatic cohort, expression pattern of 377 mature microRNAs were detected in primary and paired metastatic tissues from 17 CRC patients. The results showed that miR-133b significantly downregulated in liver metastatic tissues compared with their paired primary CRC tissues, and markedly downregulated in all the 12 CRC liver metastatic tissues. The major concern is why the authors only chose to analyse miR-133b expression between liver metastatic tissues and their paired primary CRC tissues? A recent study identified the microRNA signature between colorectal recurrences to lymph nodes and liver and between colorectal liver metastasis and primary hepatic tumour (Drusco et al, 2014). Wang et al (2013) also chose to reveal has-miR-337-3p expression in the metastatic tissues, lymph node metastatic tissues, and the primary gastric cancer tissues. Therefore, we think it would be more persuasive if this study also analyses miR-133b expression in lymph node metastatic tissues.