The NCI has retired its instance of the Cancer Molecular Analysis Portal https://cma.nci.nih.gov . Please use following resources to access TCGA, TARGET, and REMBRANDT datasets going forward:

TCGA
cBIO Cancer Genomics Portal, http://www.cbioportal.org
TCGA Data Portal, https://tcga-data.nci.nih.gov/tcga/
Cancer Genome Workbench, https://cgwb.nci.nih.gov/

TARGET
caIntegrator, https://caintegrator.nci.nih.gov/caintegrator/
TARGET Data Portal, http://target.cancer.gov/dataportal/
Cancer Genome Workbench, https://cgwb.nci.nih.gov/

REMBRANDT
caIntegrator, https://caintegrator.nci.nih.gov/caintegrator/
REMBRANDT Data Portal, https://caintegrator.nci.nih.gov/rembrandt/